Leo Valdez

Leonidas "Leo" Valdez is a Greek demigod, the son of Hephaestus and Esperanza Valdez. He is one of the seven heroes of the Prophecy of Seven. After sacrificing himself and being resurrected using the Physician's Cure, he rescued Calypso out of Ogygia. He is currently living with Josephine and Hemithea, while going to high school with his girlfriend Calypso.
== History ==
=== Early Life ===
Leo was born in Houston, Texas, to the mechanic Esperanza Valdez, and the blacksmith god Hephaestus. Unlike most of his half-siblings, Leo has the rare ability to control fire. He is the first child born of Hephaestus to be able to control fire in centuries.
When Leo was just a baby, his mother took him to see his bisabuelo (great-grandfather), Sammy Valdez. Sammy was overjoyed to see Leo and held him, chuckling and tickling his chin. Sammy told him about Hazel, and said he would not live to see her again. He told his great-grandson that a woman named Doña Callida had warned Hazel's danger would not happen in his lifetime, but he'd promised he would be there for her. He then told Leo to tell Hazel that he was sorry, and told him to help her. He told him to apologize on his behalf for selling the diamond and that the diamond came with a curse: he never saw her again. He gave his great-grandson his blessing and said Leo was special, just like Hazel.
Leo was about two when Tía Callida decided to lay Leo down for a nap and said she wanted to see if he was her brave little hero. She nestled him in blankets and laid him in what Leo thought were red and yellow pillows, but realized later was actually a fireplace. He remembered sleeping comfortably and grabbing at sparks. He dreamed of being on a boat made of fire, and Tía sang him lullabies as he slept, in Greek. He didn't know what the language was at the time. When Esperanza came home, she was furious, went to take Leo from the flames, and yelled, "How could you?", but Tía had disappeared.
Tía continued to show up at his house, and when he was three, she let him play with knives, saying that he needed to learn his blades early if he wanted to be her hero someday. When he was four, she found him a rattlesnake from a cow pasture, gave him a stick, and told him to poke it to show that he was brave, and that the Fates were right to choose him. He didn't poke the snake as it didn't seem fair, and it disappeared into the grass.
The last time Tía Callida watched him was when he was five. She brought him paper and crayons, and sat at a picnic table under a pecan tree while Leo drew. As she sang songs, Leo drew the boat he'd dreamed about - what would become the Argo II - with crayons. When he was about to sign his name, it flew away. Tía told him that it wasn't time yet to be a hero, and that he would find his destiny, but first he had to face many sorrows. She then told him to make a fire to warm her old bones. A few minutes later, Esperanza came out and shrieked when she saw him sitting in the middle of a fire, with his hands burning the picnic table, and the crayons melted into goo. The fire left his handprints in the table, leaving the people in his apartment complex to wonder for years how he did it. After the visit, Esperanza had a talk with him and said she couldn't come back again, and that he wasn't ready to be a hero. She told him to never use fire again until he met his father, and when he did, he would explain everything.
He and his mom were very close. She taught him Morse code, and they would communicate simple things with it, tapping messages on the walls. Esperanza would switch between English and Spanish when she talked to him, and made him bilingual. It took years for him to realize not everyone spoke that way. His mom worked at her machine shop since no one would hire her, providing for the both of them. She consistently told him that he would someday meet his father, but would not answer questions about him. By the time Leo was eight, he spent every spare minute at the shop, knew how to use the machines, and could do math better than most adults, solving mechanical problems in his head. They would also have special Friday night dinners of shrimp and catfish from a local seafood restaurant in Houston.
Leo had a cousin who bullied him, named Raphael, and a mean third grade teacher named Mr. Borquin. During Día de los Muertos, his Aunt Rosa took it seriously and dragged him to the local cemetery in Houston, where they would clean their relatives' graves and leave offerings of lemonade, cookies, and marigolds. Rosa would force him to stay for the picnic, as if eating with dead people would fix his appetite. 
In The Blood of Olympus, Leo recalled how he used to play with plastic organ models as a kid. He once got in trouble after turning a cross-section kidney and some skeleton legs into a kidney monster, and scared the school nurse. In kindergarten, he was taught how to sign his name.
=== Death of Mother ===
One night, when Leo was eight, Esperanza and Leo were working late at night. Esperanza was making a prototype for a drill bit, and if she sold the patent, they would finally get a break. While they worked, Leo helped out by passing her supplies and made corny jokes to keep her spirits up. Esperanza would laugh at them and say his father would be proud of him. After they were done, as they were walking through the break room, Esperanza realized that she left her keys in the warehouse and thought she had them, and smiled at Leo for the last time. A few seconds later, the door closed and locked. Leo heard something heavy crash, and tried in vain to open the door. He then tapped with Morse code, "You okay?". But then a woman appeared, and explained that Esperanza couldn't hear him. The woman turned out to be Gaea (though Leo was unaware at the time). She was asleep with black robes made of earth and a veil that covered her face.
Leo thought she was Tía Callida, but she said she wasn't, just a family resemblance. He asked where his mom was, and she said that he will fight her children someday, and that when they would try to wake her, Leo would try to prevent it, which Gaea did not want. Leo said he didn't want to fight anybody, and Gaea said that she could not destroy him yet, because the Fates wouldn't allow it. But Gaea said that they didn't protect Esperanza, and that the Fates could not stop her from breaking Leo's spirit. She told him to remember this night, when they ask him to oppose her. Leo became angry and told her to leave his mother alone, and she asked how he would stop her. His hands caught fire as he realized he was the only thing standing between the woman and Esperanza. Leo lost consciousness as the room went up in flames, burning down the shop with his mother trapped inside.
Leo woke up in an ambulance, and the paramedic was kind to him, saying that the warehouse had burned down and his mom hadn't made it out. Leo felt hollow, and realized he had lost control like his mom had warned him about. He thought her death was his fault. The police were not nice to him and said the fire started where Leo was standing, and he miraculously survived, but his mom didn't make it. The police wondered what kind of child would've started a fire. His neighbors in the apartment complex gossiped about him, saying they always knew something was wrong with him. 
=== Life in Foster Care ===
His Aunt Rosa turned his entire family against him and called him a diablo (meaning "the devil"), and shouted at social workers to take him away. Leo never forgave Rosa for that, and kept a grudge against her for the rest of his life. Rosa would forever be the person Leo hated most. His relatives wouldn't take him in, so he was sent to foster care. His first foster home only lasted for a few days, as he ran away a few days later.
He would be at five more foster homes after that. Some foster homes would last longer than others and he would make friends, joke around, and pretend that nothing bothered him, but he always ran away sooner or later. At the foster homes he was at, he was frozen out and ignored, and they often treated him like they didn't need him. He even had an abusive foster mom, Teresa. From being in foster care, and in rough schools, he learned to tell when fights were going to get ugly. He would have nightmares and hug his pillow, which he thought was embarrassing in the foster homes. 
Leo was bullied when he was younger by popular girls, who would make fun of him, gossiped a lot, and did everything to make his life miserable. He would tease bullies, make them laugh, and mess with them to save himself.
Whenever Leo was between foster homes, he would sleep under the Houston bridge for around a month.
=== Wilderness School ===
After Leo ran away for the sixth time, when he was fifteen, he was caught by a truancy officer in New Mexico. He was taken to court and sentenced to go to the Wilderness School in Nevada, a correctional facility for delinquents, where he would stay for almost half a year. While Leo was there, he was protected by Coach Hedge and befriended Piper McLean, with whom he shared secrets with: Leo learned how Piper's dad was a celebrity and how she stole a BMW, and Piper learned how Leo ran away six times. Leo hated being at the Wilderness school, likening it to a prison, and would have to run ten miles a day and be pushed to his limits. It also forced Leo to go on several forced marches. However, he liked to mess with Coach Hedge. 
Leo was given fake Mist memories of Jason Grace being there for four months before he left, and Leo and Jason became best friends. They would joke about Piper, and Jason would be fine with Leo's annoying jokes. In the Mist memories, Piper and Jason had started dating a few weeks before the beginning of The Lost Hero. Even though Leo was happy for them, he felt like the third wheel and that they didn't need him anymore.
==The Heroes of Olympus==
===The Lost Hero===
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Leo goes to the Wilderness School with Piper and Jason. He partners up to complete their assignment with Jason on their field trip to Grand Canyon. During the ride there, Jason says he does not remember anything and Leo thinks that he is playing a joke on him. When Gleeson Hedge, their coach, yells at them from the front of the bus, Leo says that he can not hear him, prompting Hedge to use his megaphone. When Hedge turns on the megaphone, it sounds like Darth Vader or shouts out phrases like "The cow says moo." Leo pranked him by mechanically modifying his megaphone. He seems to be good friends with Piper and Jason at first and he seems to know Piper very well, knowing who her dad is and being able to tell that she likes to fight her own battles when she is picked on by some of the mean girls on the trip. When they are walking across the sky-walk, a storm appears around them, and Leo is the one that notices the storm is only in this area and nowhere else. As the storm begins to get bad, most of the students run away back inside except for Jason, Leo, Piper, Dylan, and Coach Hedge.
Dylan reveals himself to be a Ventus, or a storm spirit and attacks the others with the help of two other ventis. Leo is thrown off the sky-walk and slams into one of the canyon walls. While Jason and Piper try to fight Dylan, Hedge takes off his disguise and shows the others that he is a satyr sent to protect Leo and Piper. He jumps over the side and manages to grab Leo, pulling him back up as Jason fights off the venti using his Imperial Gold sword, Ivlivs thus saving him. Hedge manages to get Leo back onto the sky-walk, where Dylan tries to abduct him. At the last minute, Hedge intervenes and is abducted instead.
Annabeth Chase and Butch arrive to rescue them on a flying chariot, bringing the three demigods to Camp Half-Blood. While on the way back, Leo makes a few jokes about how Butch is a child of the rainbow goddess, Iris, and is one of the best campers with the pegasi. When Butch threatens to toss him off the flying chariot, Leo sarcastically backtracks saying that rainbows and ponies are very macho. Once arriving at camp, Leo is immediately claimed by his father, Hephaestus, and goes on a tour of the camp with Will Solace, a son of Apollo and head counselor of cabin seven, who brings him to Hephaestus's cabin. It is here that he meets Jake Mason, the current head of the cabin. Jake is in a full-body cast after trying to stop the Bronze Dragon that has started going crazy and attacking the camp. He also explains that after Charles Beckendorf's death, the cabin has been under a curse that makes any creation of the cabin turn to junk. When Leo asks if anyone at the cabin can control fire, one of the members of Cabin 9, Nyssa, tells him that only a few people in history have ever had that power and it is considered a curse because it normally causes great destruction.
That night, at the campfire, Leo is very quiet until Rachel Elizabeth Dare gives out a quest to Jason. When Jason is about to pick which member will go with him and Nyssa volunteers herself, Leo stands up and claims that it is him that must go on the quest, offering that he also has an idea on the transportation problem. Jason says that if he can get them away to fly, then he can go with them. That night, Leo goes into the woods looking for the bronze dragon and stumbles upon a trap set up by Cabin 9 to capture it. The dragon appears in front of Leo, who is upset that the dragon does not have wings to fly. The dragon blasts him with fire, but Leo's body is unharmed because of his Pyrokinesis. After it falls into the trap, Leo takes the chance to find the control panel and fix some of the wirings inside its head. After he fixes him up the best he can, the dragon asks Leo to climb on his back and takes him to Bunker 9 where he finds a magic toolbelt and a set of bronze wings for the dragon. He spends most of the night working on the dragon and appears in front of everyone the next morning saying he found Jason and Piper a ride, naming the dragon Festus meaning "happy" in Latin. When asked where he got the wings, he says he found them in the woods but does not mention the bunker. Jason keeps his promise and chooses Leo as the last member of the three campers to go on their quest to save Hera.
They begin to fly to Quebec, Canada to talk to Boreas to find out where to find Hera. They meet the two sons of Boreas, Zetes, and Calais. The brothers say that they can't land unless it's an emergency landing, so they trick them into letting them into Boreas's palace. Festus is not allowed in as he is a fire dragon, so Leo flips a switch and Festus turns into a suitcase (but still weighs the same, which is 6 billion pounds). Luckily, Festus in suitcase form has wheels. When Khione, the snow goddess, comes down the stairs, Leo immediately falls in love with her as soon as he sees her, but she dislikes him because she can sense that he can summon fire (as Boreas's children can smell fire). He is not allowed to meet with Boreas as ice and fire would not be ideal in this situation. While his friends were gone, he has his clothes cleaned of the oil and dirt gathered on him from fixing Festus. Leo is upset that Jason and Piper made Khione mad because he was planning on making her his prom date, not knowing that she likes to collect demigods as ice statues. Jason later explains this to him, which Leo thanks him for.
After they leave, Festus is knocked out of the sky and crashes into an abandoned car factory while Leo was resting. Leo runs off to go and find where Festus landed, which turns out to be in a row of portable toilets. When he looks inside the dragon's head, it is shown the reason Festus crashed was that the wiring had frozen over, something that shouldn't have happened as it would have been too hot inside his head. While he is fixing the dragon, the face of Gaea appears in the snow, sludge, and dirt and tells him to walk away from his friends and let him die. He tosses one of the toilet lids at the face and the face disappears.
When he gets back to the factory, Jason and Piper have been captured by three cyclopes called Ma Gasket, Torque, and Sump. Piper sees Leo sneaking around and keeps the monsters talking while he creates a remote to control some heavy lifting machinery. When one of Ma's children leaves, he uses that moment to attack, taking out her son by tossing him through the roof and then crushing the other with a metal claw when he returns. Ma Gasket is also defeated when Leo uses his fire to break a chain, causing an engine to fall on top of her. When he goes to free Piper and the unconscious Jason, the dust of the cyclopes begins to reform. He rushes them back to Festus, hearing them reform inside the factory. Piper thinks that his fire powers are cool, but he still feels like they are a curse because he thinks that it was his fire that caused his mom's death. He also tells them that children of Hephaestus are only born with fire powers when bad things are about to happen, but Jason cheers him up by suggesting that they are born with those powers because that is when they are needed most.
When they arrive in Chicago, Leo takes a whistle out of his pocket and teaches Festus to come when he is called. After that, the group follows a group of storm spirits into the sewer system where they get some rest while Leo makes some food for the other two. They follow the wind into a shopping mall, which is owned and operated by Medea. They find that in Medea's mall, Coach Hedge and some venti are locked in cages. Medea begins to charmspeak the trio, but Piper is able to resist. Leo and Jason begin shopping for new clothes, potions, and soon forget the reason they were there in the first place. Medea soon turns Leo and Jason on each other and tries to force them to kill each other. Piper, trying to get them back to their senses, gets Medea to admit that she can see the future and told her patron about Leo being one of the seven, leading to the death of his mother. This is enough to break the spell over Leo and Jason, but Medea lets loose the Sun Dragons to fight them off while she escapes. He calls Festus who can fight off the other two dragons and the three fly off with Coach Hedge and the venti while the mall is destroyed thanks to Piper.
As they are flying, Leo falls asleep and has a dream of his father Hephaestus, who is using an old pirate radio broadcaster to speak to Leo without Zeus knowing. At first, Leo is very angry with him for not coming to see him sooner but softens after seeing that his father acts the same way he does when he is nervous (fiddling with gears and small machines). His father tells him that the gods closed themselves off from their children because of Zeus's orders; partly because he felt that their children should respect them and he felt ashamed that the gods needed the help of mortals, and also because Zeus was worried that their activities on Earth were awakening Gaea. Not long after the dream starts, Zeus picks up on the dream and cuts the connection.
When Leo wakes up, Festus is crashing to the ground and he tells Jason to carry Piper away. Jason is unwilling to leave his friend but does so anyway while Leo tries to reboot Festus. Once the dragon comes back online, it is already too late and the crash into the yard of a large house. Leo survives from the crash. When he comes to his senses, Festus is destroyed by the house's defense system (lasers) and Leo asks his father to bring his head back to Bunker 9 so he can reuse him, as that was Festus's final wish. Leo takes it very hard and thought it was his fault, leading Festus to his death. But soon, Jason said he couldn't do better, Festus was the best dragon he had ever seen.
The house turns out to belong to King Midas and his son Lityerses. At first, all seems to be going well until Midas turns Piper into gold and when he tries to fight him with his fire, he can't (the gold suppresses his powers). He is also turned into a gold statue but is freed after Jason defeats Lityerses and washes off Leo and Piper in the river, which is freezing cold. Jason uses the storm spirits to fly them away from the house and after setting up camp, Leo makes tofu burgers for Piper and the newly freed Coach Hedge.
Not long after, they are attacked by a pack of wolves lead by Lycaon, the first werewolf. He says that their weapons will not work on him because he can only be hurt with silver, but Leo pulls some gasoline out of his belt and lights some of the wolves on fire, but it isn't enough to hold them back. He is only saved thanks to the timely arrival of the Hunters of Artemis that shoot the wolves with silver arrows. Leo immediately likes Thalia after only seeing her for a second and thinks that she is too hot to be Jason's sister, but doesn't tell him that. When the Hunters set up camp, a few hunters go to take care of Piper and Leo begins to follow them, only for Jason to ask him to stay as he begins talking to his sister. He learns about how he was separated from his sister and about Jason's mother, making him feel bad for Jason.
When Piper is fully healed, the group begins to travel to Aeolus' palace, but on the way up Leo asks why a wind spirit would need a bridge, to which Thalia says it is an anchor so that it doesn't fly away. Leo gets an idea from this about what Hera said about Jason being a bridge, and a bridge must connect to something. His mind begins to race so fast that his fire powers heat his body and the bridge begins to crack. Jason manages to get Leo to the palace, but Thalia is left behind and says she will meet Jason at the wolf house.
After returning the venti and finding the location of Piper's father, Aeolus gives Leo a drawing he had made when he was only a small child and tells him that it is the key to his success. Soon after, he turns on the heroes after a voice tells him to, someone that is above the gods. Mellie, the wind nymph, helps them in their escape and when he wakes up, they are in a diner in San Francisco and Leo has a set of new clothes (thanks to Aphrodite, who had visited Piper in her dream). Piper tells them they are fighting Gaea and they should be careful from now on and avoid walking on land. They take a cab to Mount Diablo and begin to climb to the top, but Leo's feet begin to sink into the ground as Gaea is starting to wake up.
As they get closer, Leo makes a small wind-up toy but isn't sure what it does, as he wasn't paying attention when he made it. When they reach the summit, Enceladus is waiting for them and summons a group of Earthborn to attack them. Leo tosses his toy into one of the construction vehicles and hops into another one, using the machine to destroy several of the monsters while Jason is fighting the giant. Soon, the vehicle is destroyed, but his windup toy activates the other piece of equipment and it begins destroying more monsters until it too is deactivated. One Earthborn was left, but Leo had no more tricks or weapons. He lit himself on fire (he called this the blaze of glory) and charged, only for a dagger to chop the monster in half thanks to Piper.
Jason (with a lightning bolt from his father for help) defeated Enceladus and saved Piper's dad, flying back to the airport where Piper charmspeaks a pilot. Once they land and everyone is safe, they receive an Iris Message from Thalia that she found Hera at the Wolf House, so they borrow the chopper with Leo as the pilot. He can fly the chopper well enough thanks to his mechanical instincts, but sleet began to hammer the helicopter and they crash into the middle of a battlefield. They all retreat to the Wolf House, but Khione arrives and freezes all the Hunters, allowing the wolves and Earthborn to walk into the front door. She tells them that she was the one whispering into the ears of the gods and watching them for Enceladus. She was also the one that froze Festus' wiring and plans on killing Jason and Piper so that the Roman campers will find their bodies and think that the Greeks have sided with the Giants. She offers Leo a place at her side because he is interesting, but he laughs her off and starts fighting her with his fire. The heat of his attacks begins to melt the ice and snow and many of the monsters run away in fear, including Khione herself as she turns to snow and disappears.
Leo then gets to work freeing Hera with an electric saw which he connected to a Ventus named Tempest which was under Jason's command while Piper tries to charmspeak Gaea back to sleep to make the cage easier to break. While they do this, Jason is fighting off the newly awaken Porphyrion. Once the main support of the cage is broken, Hera broke free causing any monsters left in the house to run away or be dissolved by her true form. Porphyrion managed to get away, not wanting to fight when not at his full strength and Hera returns the demigods to camp. The trip causes Leo to throw up in one of the offering fires to the gods.After telling everyone about their trip, Leo shows Piper, Jason, Chiron, and his cabin members the entrance to Bunker 9 and his fire powers. After searching the bunker, they find weapon ideas and designs, including a large warship that matches the picture of the flying boat that Leo had drawn when he was a child. His cabin members elect him as Cabin Leader and make plans to make the Argo II and fly to Greece. He later attends the War Council as the leader of his cabin and wonders why Jason picked Annabeth to sail with them. Jason then explains that if he is here at Camp Half-Blood, Percy must be at the Roman camp, called Camp Jupiter and that the Roman campers aren't as nice.
===The Son of Neptune===
While Percy is dreaming, he sees Leo working on the Argo II when one of the engines explodes. He claims that it could take two or three days to fix and that the deadline to have the ship completed was today. When Percy, Frank, and Hazel are watching Polybotes from afar Ma Gasket, the Cyclops from The Lost Hero yells, "The camp, yes. Vengeance! The orange and purple ones destroy my home. Now Ma Gasket will destroy theirs! Do you hear me, Leo? Jason? Piper? I come to annihilate you!"
Later, when visiting Hazel Levesque's house in Alaska, Percy sees a picture of Sammy Valdez and thinks he had seen him somewhere before, but can't remember where. Hazel says he would be much older and Percy must just be imagining things. Percy then remembers his dream figuring out that Leo resembles Sammy almost identically.
Upon returning to Camp Jupiter and the defeat of Polybotes, Leo appears on a video scroll that was sent to Percy through Ella. He told them that he would appreciate it if the Roman demigods didn't shoot them out of the sky when they come to rescue Percy and start their quest. While watching the video, Hazel mistook him for Sammy Valdez and Percy remembers the picture of Sammy when looking at Leo.
===The Demigod Diaries===
====Leo Valdez and the Quest for Buford====
When Leo accidentally polishes Buford with Windex instead of Lemon Pledge with extra moisturizing formula, Buford runs off with two syncopations essential to building the engine for the Argo II. Leo, in a panic, asks for Jason and Piper's help to retrieve them. He explains the situation of how in about an hour, dangerous chemicals will mix in the engine blowing up the forest portion of Camp Half-Blood without the syncopations. With everyone caught up, the three friends journey into the forest in search of Buford. They then encounter Maenads on their journey and Leo feigns to be the Greek god, Dionysus, to please the Maenads. Suspicious, the Maenads figure out the truth and chase Leo and his friends until Leo comes up with an idea. Leo sends Jason to go find Buford, while he and Piper run towards Bunker 9. Once they reach Bunker 9, Leo distracts the Maenads with a party while he sets up a trap to ensnare them. Leo finally sets off the trap which drops a net (based on the original net which Hephaestus used to catch Ares and Aphrodite together) on the Maenads. Jason just in time arrives with Buford and Leo fixes the syncopator in the engine of the Argo II, thus narrowly preventing a massive explosion at Camp Half-Blood. Later Chiron and Argus arrive and decide to deport the Maenads away.
===The Mark of Athena ===
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Leo is one of the five crewmates aboard the Argo II when it arrived at Camp Jupiter. He is possessed by an eidolon and attacks Camp Jupiter and New Rome. Percy is forced to knock him out while Annabeth piloted the ship away from the Romans. Following this incident, Leo wonders if his friends could ever trust him. Frank Zhang asks Leo if his name was Sammy, but he denies it. Hazel Levesque soon reunites with the others as they land in Utah. Leo informs the others that he needs supplies to get the Argo II working again. Hazel volunteers to go and throughout the journey, they share many awkward moments, much to Leo's dismay.
The two soon encounter Nemesis who Leo, at first, thinks is his Aunt Rosa. Nemesis tells him that he would always be the seventh wheel and offers her help in taking down the pride of mighty, which she claims Gaea and the Gigantes to be the proudest of all. She gives Leo a fortune cookie and tells him that he'll open it when he needs it most, but a painful sacrifice must be required. Leo tries to return it, but the fortune cookie seals itself away in his tool pocket. The goddess states that they had to save Nico by July 1st, the Kalends of July before Rome is destroyed. Nemesis then tells Leo to meet her cursed boy in the lake, before night where he gets agitated.
Leo and Hazel then meet Echo who Leo teases by having her repeat silly phrases. Echo leads them to Narcissus and his nymph fan club. Leo notes that Narcissus is looking at his reflection with a sheet of celestial bronze, one of the items needed to fix the ship. The demigods manage to figure out that Echo is trying to help Narcissus change his ways, but has proven unsuccessful. Leo tries to talk Narcissus into giving him the celestial bronze but fails. He then comes up with a plan and stations Hazel a few feet away and Echo in the nymph crowd.
Drawing tattoos on his arm and greasing his hair with motor oil, Leo struts out toward the love-struck boy and claims he is better than Narcissus. Echo repeats everything Leo states, and manages to trick the nymphs into thinking that Leo is better, much to Narcissus's dismay. Distracted, Narcissus declares he is better as Leo continues to insult him. Hazel, using her powers, draws the celestial bronze towards her and runs toward the ship. Narcissus takes notice of the trick and orders the nymphs to catch the demigods. Leo helps Hazel with the sheet as Arion comes to their rescue. He tries to persuade Echo to come with them, but she decides to help Narcissus and kisses him on the cheek. Leo states he'll never forget her, but his memory of her smile starts to fade as they reach the ship.
Leo grabs the supplies and manages to put the engine back together while Percy holds the nymphs back. The Argo II then heads back into the air, setting sail toward the Atlantic Ocean. He later calls a group meeting where they exchange notes on their enemies, and Hazel reveals that Rome would be destroyed in six days. Leo tells the group that he has to put down to finish repairs. Annabeth suggests someplace out of the way, but close to a city when Piper suggests Kansas. In the morning, Leo thanks Piper for not hating him after attacking New Rome the previous day. Piper then reassures she'll stick up for him and compares him to the annoying little brother she never had. On the deck, Piper explains her vision of Bacchus and Topeka 32. Leo states he and Festus calculated the mile marker as best as they could. He stays on board to fix the hull while Piper, Jason, and Percy head into Kansas. However, the trio soon realizes that his calculations were wrong and are forced to summon Blackjack and Tempest for transportation.
Leo helps Annabeth carry Jason and Piper toward the sickbay. He then heads the ship to Atlanta and retreats below deck for another meeting. He stops blaming himself for the attack on New Rome when Piper tells him that eidolons, possessing spirits, made him do it. The group discusses Ephialtes and Otis, the twin giants, and how Romans would not follow them into the Mare Nostrum. Piper also informs that Gaea wants two of the seven demigods to be killed. Leo remembers how Khinoe had stated Jason's blood would taint the Wolf House forever. He then proceeds to wonder if demigod blood has that power. Percy states that Polybotes had stated Percy's blood at Mount Olympus would wake Gaea.
Piper later states that the eidolons were still in the room and calls out to them with her Charmspeak. Leo tries to laugh her attempt off but is taken over by the eidolon along with Jason and Percy. Piper tells the spirits to swear on the Styx that they would leave the ship and never possess anyone on the ship again. The eidolons leave which results in Leo falling on the floor because Frank didn't catch him. The next day, Leo grins when Percy and Annabeth are caught together in the stables, muttering classic over and over. At another meeting, Percy explains his dream about the twins and Nico. Leo makes a theory that Nico may be conspiring with the enemy while Jason backs him up. Hazel, outraged, storms out of the room, while Leo tries to apologize. Frank stops him angrily and Leo leaves to land the ship.
Percy, Frank, and Coach Hedge embark into Atlanta while Annabeth attempts to cheer up Hazel. Jason, Piper, and Leo are interrupted from their lunch to disembark, causing Leo to cry out if he can ever just eat a normal lunch. Percy tells him to head to Charleston where they can find a map to the Mark of Athena. Percy and Frank recount how they had met Phorcys, Keto, and the imprisonment of wild animals. They had also been imprisoned but escaped causing Leo to wonder if he's worth as much as two or three Franks. Frank, meanwhile gets himself trapped in Chinese Handcuffs, much to Leo's amusement. He changes into a lizard to escape which Leo jokes about. Percy then states that the map leads to the Mark of Athena causing them to wonder what it is.
Annabeth gears the conversation back to Charleston and wonders why Jason looked surprised at the name. He explains how he and Reyna had salvaged a ship, the C.S.S. Hunley for supplies, much to Leo's excitement claiming he wanted to see the Civil War artifact. Jason later explains how the Romans had fought for the Confederate side, much to Hazel's distaste. He then apologizes for it and his outburst in the meeting, forcing Leo to do the same. Jason then states he could lead a team to search for the map at the museum, which Leo volunteers for. Jason recruits Frank, who was playing with the Chinese handcuffs and couldn't get his fingers out. Leo laughs at Frank, stating there's a simple trick for escaping. He then mocks him in Chiron's voice when Frank turned into a lizard to escape. Jason then states that Reyna had a meeting with a ghost and she was never the same. Since the ghost only met with females, Annabeth, Piper, and Hazel agree to go.
Leo informs that Roman eagles were in their way and how he could send Buford as a distraction and go the long way to Charleston. Hazel then pleads that Nico would have less time, but Leo reassures her they'll have barely enough time to reach Rome and sends Buford, with a pair of Frank's pants, on his way. The next day, Leo docks the ship at Charleston Harbor and leaves with Jason and Frank to the museum. At the museum, they are attacked by Confederate ghosts and head back to the ship where Piper sends them an Iris-message that they're heading for Fort Sumter and Romans are attacking. Frank turns into a bald eagle while Leo grabs his talons and flies toward the Argo II with Jason behind them. Coach Hedge fires the ballista and knocks the three off course. Leo is dropped and the three disappear behind the fort. Annabeth tells them to drawback as she enters Fort Sumter, successfully obtaining the map and reunites with them back on the ship.
Leo desperately tries to man the ship as Percy and Jason create massive storms to keep the Roman demigods away. Leo punches in coordinates that Percy received from a nereid and they set sail into the Atlantic. After putting some distance, Coach Hedge takes the wheel and Leo asks where they are heading. Percy informs that the nereid had said Chiron's brothers would help them and that Keto is bound to send one of her sea monsters their way. Jason suggests they fly, but Leo says the air stabilizer is busted. Hazel worries and states Nico only has three days left, but Leo reassures her they'll make it if something unexpected happens. Frank wonders if there's any good news which Leo replies that Buford had successfully returned but without his pants. Annabeth and Piper tell Frank to help them take Jason and Percy, who was sapped out of strength, below deck. Leo wonders if he forgot something, but tries to dismiss it.
Hazel and Leo then stare at each other awkwardly and Leo tries to help her with her seasickness. Hazel reassures Leo that Frank is a nice guy, but he is just nervous about his fire. Hazel asks Leo to remember what had happened in the Great Salt Lake, and Leo states he'll be willing to use the fortune cookie to find Nico. Hazel rebuffs this and instead reminds him of how he handled Narcissus and the nymphs. She states that he reminds her too much of Sammy and she can show him who he was. Leo, determined to do what Frank did, grabs Hazel's hand and she shows him a flashback of her life.
Ghost Hazel and Leo watch as Hazel, bullied by Rufus, is saved by Sammy. Rufus had demanded Hazel for a diamond, but Sammy managed to take it instead, much to Hazel's horror. Leo is shocked that Sammy looks so much like him, but that he was smarter, cooler, and funnier. He figures out Sammy had stolen Hazel's heart, but he wasn't Sammy. The memory dissolves and the demigods arrive in Houston. Hazel states that this isn't from her memory, but Leo discovers that this is the spot where both of their timelines connect. An old man on the porch states Hazel's name and Hazel discovers Gaea had lied. Sammy was alive and well beyond the 1960s. Using Morse code, Sammy was tapping I love you over again to Hazel. Leo's mom carries Leo to Sammy and tells him that he is Leo's bisabolol, meaning great-grandfather in Spanish. Sammy takes Leo and tells him he'll be his stunt double, but Hera had stated he wouldn't be alive for Hazel's great danger and pleads to tell her he was sorry for selling the diamond. Sammy claims it was a good life, but it was cursed. He never saw Hazel again. Hazel starts crying as Sammy tells Leo he has his blessing and tells her hello to Hazel for him. He returns Leo to Esperanza and says he is ready to rest soon as the scene dissolves.
Back on the Argo II, the ship lurches to one side and Coach Hedge warns that one of Keto's monsters had found them. Leo curses himself for not changing the sonar as a skolopendra attack. The rest of the crew head upstairs, but Percy and Jason are too tired to fight. Annabeth and Piper try to attack with their daggers as Frank shoots arrows and Coach Hedge attacks with his baseball bat. The satyr tells Leo that if he wasn't holding hands with Hazel for so long then the monster wouldn't have attacked. Frank, outraged and distracted, is knocked overboard. Leo and Hazel open a crate and take out jars of Greek fire. However, they are trapped by one of the monster's tentacles. Leo burns fire onto the tentacle and the monster drops them. Hazel and Leo throw the Greek fire into the monster's mouth as they sink underwater and slip into unconsciousness.
Leo wakes up in an underwater dungeon with Frank. He manages to convince him that he and Hazel are just friends, which Frank believes. The two then try to figure out a way to escape and Leo covers himself in fire, much to Frank´s horror as he backs away from him. Leo puts out the fire and Frank hesitates to tell him about his weakness. Just at that moment, the two are visited by a fish-horse otherwise known as ichthyocentaur. Frank is taken by Bythos, the combat teacher, while Leo is interrogated by Aphros, the home economics teacher. Leo tells Aphros his story which matches Hazel's much to Aphros's delight. Hazel reunites with Leo while Aprhos heads to find Frank. Leo manages to figure out that Frank's life is connected to a piece of firewood. Aphros, Bythos, and Frank meet up with Hazel and Leo where the ichthyocentaurs reassure that they will take action against Phorcys and Keto. Aphros tells Hazel to visit again with Arion and to save Nico the day after tomorrow as he will be vital to the quest. Aprhos informs Leo that he needs to stay close to Frank and Hazel because they will face mechanical difficulties and sends them on their way with brownies.
The four demigods and Coach Hedge are relieved to see the three again as they make their way deeper into the Atlantic Ocean. They inform the crew that the ichthyocentaurs would protect the ship until they reach the Mare Nostrum. Percy, however, is disappointed that they didn't want to meet him. Leo informs them they'll spend the next day flying to Rome and then the day after that, they'll arrive. Percy brings up the Mark of Athena, much to Annabeth's discomfort, calling it a problem. Annabeth tells them that the map she found would only show itself to her, but passes around a coin she received from her mother. Annabeth informs that the Mark of Athena would lead her to the Athena Parthenos, which vanished. Jason states that when he was praetor, an old legend was passed around that the Romans stole the statue, and that's why the two sides can never get along. Annabeth states she has to find the statue so she can mend the rift. After the meeting, Leo then assigns chores for everyone to do around Argo II.
The next day, the group arrives at the Rock of Gibraltar, otherwise known as the Pillars of Hercules. An island appears in their way, blocking the path. Jason states that Hercules might be on the island and that he'll want to talk to them. Annabeth sends Jason and Piper on the island to converse with him while the others stay on board. Leo manages to fix the stabilizer in time for Piper's plan to unfold. The group manages to enter the Mare Nostrum as they fly away from Hercules. That night, after countless attacks, Leo stays manning the wheel while Percy and Annabeth discuss Percy's recent dream. However, they are attacked and kidnapped by a pirate, Chrysaor. The pirate kidnaps Piper, Hazel, Leo, Coach Hedge, and Annabeth while Percy and Frank manage to trick him away. Percy later pays tribute to his victory to Bacchus, and they sink the pirate's ship. The next morning, the group arrives in Rome.
Leo accompanies Hazel and Frank to the Pantheon where he discovers an underground tunnel behind the Tomb of Raphael. Hazel decides to head inside first, but Leo and Frank are forced to follow when they are attacked by eidolons. The trio heads down the tunnel and enters a workshop, to Leo's delight. He exclaims that the inventions were the work of Archimedes and how he could upgrade the ship with his plans. However, Hazel and Frank are shocked by some of the incomplete inventions, controlled by eidolons, rendering them unconscious. Before they can get to Leo, he runs towards a room with folding metal gates and seals them together. The eidolons threaten to destroy the Archimedes Scrolls and kill Hazel and Frank unless Leo exits his prison. Leo tries to scan his surroundings and finds an Archimedes Sphere. He rapidly puts together the sphere but doesn't have the access code as the eidolons prepare to attack. Leo breaks open the fortune cookie he received from Nemesis and manages to complete the sphere. Leo manages to destroy the Taser Ball and possess one of the eidolons to battle the other one. Frank shields Hazel with his body and duck as Leo destroys the eidolons. Hazel wonders where Nico could be and Leo points to Nico's Sword and states it was a trap. Gaea tells them that it was all a distraction as she traps them inside the workshop. She shows them visions of Annabeth facing her mother's mortal enemy and Percy leading Piper and Jason into a room.
Leo then rescues Percy, Jason, Piper, and Nico from Ephialtes and Otis as the twins are destroyed by Bacchus in the Colosseum. He states how he had Hazel create a tunnel, built and attached a distress signal to Frank the weasel, and led Coach Hedge to save them. Leo tells Percy that Gaea had shown them Annabeth in peril and they head to the Emmanuel Building. Along the way, Nico tells them that the mortal side of the Doors of Death is in Epirus, Greece in the House of Hades. He also informs that the Underworld side of the doors is in Tartarus. Leo blasts the ballistae into the parking lot, unknowingly smashing Arachne into a chasm that led to Tartarus. They disembark into the cave where Annabeth tells the group she defeated Arachne with Chinese Spidercuffs, a variation of Chinese Handcuffs. Leo thinks that they'll be able to fit the statue in the Argo II, but the lair started to collapse. Leo, Jason, Frank, Piper, and Coach Hedge try to secure Athena Parthenos from the Argo II. Hazel grabs the rope ladder but tells them to cut Annabeth's ankle. Suddenly, Annabeth is dragged toward the chasm but Percy manages to catch her in time. Nico tries to save them, but Annabeth tells Percy to let her go. Percy denies and tells Nico to promise him that he'll lead the others to the Doors of Death in Greece. He and Annabeth then fall into Tartarus.
Leo says it is his fault for Percy and Annabeth falling into Tartarus, but Nico tells them they are not dead. He still blames himself though and knows that the price for saving Hazel and Frank had been Percy and Annabeth. The six demigods decide to heed Percy's advice and Leo tells Festus to raise the sail so they can save Percy and Annabeth from the House of Hades.
===The House of Hades===
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Leo's ship, the Argo II, is attacked with giant boulders from earth spirits, known as ourae. He exclaims that he has fixed the mast on his ship three different times since they have tried to cross mountains to get to the House of Hades. Leo suggests that they wake up the others to help formulate a plan to getting over the mountains. He is shot down by Hazel twice. While they throw around ideas, Leo plays with his Archimedes Sphere and ejects a 3D image of the mountain. Hazel spots something on the horizon and tells Leo to land on the ground. Leo reminds her that he can't land on the ground because of Gaea and states that he can float close to the ground instead.
Later on in the book, Leo spends the night wrestling with the Athena Parthenos, because he's obsessed with figuring out how it works. After spending hours crawling over the stature, looking for some secret switch or pressure plate, he gives up his search and curls in a blanket to sleep in the engine room.
As soon as he is asleep, he found himself in a dream. He was running for his life through his mother's old workshop, and although he couldn't see it, he was sure something was chasing him; something dark and full of hate. When he spotted the exit and sprinted towards it, he finds Gaea blocking his path. She tells him that she wants him to meet her favorite son. Although Leo darts left, away from the goddess, her laugh still echos behind him. She also says his death is near, before Leo's dream changes.
Now he finds himself at Camp Half-Blood, except now the camp is in ruins. Everything points to a big fire blazing through the camp. Leo keeps running and feels the dark presence closing in on him. He weaves around bodies of fallen Greek and Roman demigods and wants to check if they're alive, but he feels like he's running out of time. He jogged towards the only living people he could see, a group of Romans, and notices Octavian in the midst of the conversation. Octavian turns to face him and startled Leo when he spoke in Gaea's voice, "This cannot be prevented. The Romans move east from New York. They advance on your camp, and nothing can slow them down".
Leo is tempted to punch Octavian in the face, but instead continues running, and climbs Half-Blood Hill. He falters to a stop as he notices that one side of the hill is shorn away. Beyond it, the entire world was gone, and all Leo could see were endless clouds. At a shattered pine tree, a woman kneels at a cave entrance that had cracked open between the tree's roots.
Jason and Leo go to town and are ambushed by two dwarfs. Jason is knocked out while Leo gives chase- they stole his fly. When he catches them they plead with him not to kill them. He tells them to sabotage the Romans to slow them down.
After Khione and her brothers blast Leo off the Argo II, he lands on Ogygya where Calypso complains to the gods for sending him to her as a joke. As time goes by the two warm up to each other. When he leaves on the raft he promises to get back to her. He meets up with the remaining seven, Nico and Hedge in Greece before they go to the Necromanteion. When they fight skeletons and he and Hazel get separated from the rest of the group. When they come to the mortal side of the Doors of Death they meet the giant Clytius and the sorceress Pasiphaë. She recreates the Labyrinth with the Mist, which the two make it through and through her into a mist made pit. Leo then throws a screwdriver at the Doors of Death elevator exit, to stop Percy and Annabeth from vanishing. The seven and Nico then reunite and fight the Giant before Hecate arrives and helps finish him off. Nico and Hazel then shadow-travels the group up to the surface where they meet Reyna. They all have a picnic before they decide that the seven will go to Greece and Nico will shadow travel the Athena Parthenos back to Long Island with Reyna and Hedge to prevent a civil war and help heal the incapacitated Olympians of their split personalities.
===The Blood of Olympus===
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When Annabeth, Piper, and Jason were in Ithaca, Annabeth sent Leo a morse code message to rescue Jason after he got injured. He came over with the Argo II. 
A few days later, Leo had been in the hull for days working on a secret project. Piper tried to ask him what he was doing, but he refused to tell her. Leo was actually planning to sacrifice himself and turn the Argo II into Festus. In the meantime, he also told Hazel about Calypso, who drew a picture of her for Leo. He also programmed Buford the table to have a hologram of Coach Hedge, which Piper complained about to him. He and Piper were very worried about Jason after his injury. 
Leo met for a meeting with the seven to discuss who would go to Olympia, eating the last brownie. He sat next to Jason and Hazel, because they were the least likely to punch him for his cheesy jokes. He also ate fonzies, his favorite snack from Bologna. Hazel told him that he would die if he kept eating them, but Leo said they have so much preservatives that he would live forever. Leo and the others eventually decided that he, Percy, Frank, and Hazel would go to Ithaca, because they are not competitive. Leo grabbed his collection of grenades and met them on deck.
The four arrived at Olympia and he searched the museum with Percy. They sat on a bridge overlooking the Kledos river, and it was very awkward for Leo to hang out with Percy due to their history with Calypso, and him being a survivor of Tartarus. Percy noticed that Leo was looking at him angrily and asked him why, and said that they should talk. They were interrupted by Hazel and Frank, who could not find Nike. The four looked around the ruins, which Leo was not impressed by, annoying Hazel. The more into the ruins Leo went, he became more uneasy, thinking about his past. They stopped at the Temple of Zeus, and Leo realized that was where Nike most likely was. Leo and Percy managed to summon Nike by saying that Adidas was better, and Nike and appeared. Leo asked Nike what was going on, and she split into her Roman form, Victoria. Both goddesses said that they had to fight Greeks versus Romans: Leo and Percy versus Frank and Hazel, and has to fight the Nikai. Leo tried to talk her out of it, but it was no use. The Nikai chased them and they had tone hide. 
The four planned to defeat Nike with Hazel raising the labyrinth and Leo have everyone gadgets to use to defeat her. Percy and Leo fired fake grenades that were popcorn, and distracted the Nikai. Eventually, he and Percy hid, and Percy apologized for failing Calypso, in case he didn't make it, and reassured Leo he would do anything to help them. Leo was grateful and accepted his apology, no longer able to resent Percy. Suddenly, Hazel got injured and Leo wanted to help her, but Percy told Leo to defeat the last Nikette while he helped Hazel. He defeated the last one by throwing fire at her, making her melt. Nike was furious, but Leo used the archimedes sphere to tie up the goddesses and force them to go whole with celestial bronze netting. Leo went to go find Percy and Hazel and complimented Hazel, saying she was amazing. The four then went to Nike and they learned that one of the seven would die, but they needed the Physician's Cure. They then put her in a horse stall on the ship. Leo began spending time with Nike to get advice for his plan to sacrifice himself. 
Leo later met with Piper and Frank when they returned from Pylos. Percy said that if a statue set someone on fire, they should use Leo, who said that he loved him too. Leo set the ship to fly to Sparta and made tofu tacos for everyone that night. the next morning, Leo was mad when Percy destroyed the plumbing. A few days later, on the way to Delos, the ship was battered by a storm and Leo spent days fixing it.
On the 30th, Leo decided to meet Apollo and Artemis on Delos after eating gelato, and insisted that Frank and Hazel come with him. Leo was saddened when he saw Apollo, thinking his music he was playing made him melancholy. Leo told them to not shoot, and Artemis surprised Leo by saying he expected him to be there. Leo asked why they were hiding on the island, and they explained that Zeus was angry at Apollo and wanted to punish him, since Python escaped and he encouraged Octavian. Leo asked why he couldn't tell him to stand down, but Apollo said it was no use since he was incapacitated. Apollo almost killed them, but Leo explained that he had a plan, and needed to talk to him. Apollo reluctantly decided to talk to Leo about the cure, and Leo said he needed advice to defeat Gaea. Apollo decided to hear him out and not smite him. Apollo gave Leo the advice for free, but Leo still gave him the Valdezinator he made. Apollo was very impressed and said it was the best instrument ever, and gave him directions to Asclepius in return for the instrument. Leo didn't want to give it away, but reluctantly gave it to him. He then gave him advice and got him the cursed daisy. 
After his talk with Apollo, Leo went to talk to Hazel and Frank and they exchanged the news they got, with Leo finding out about the Onagers, and Octavian's plan. Leo then told them that he needed their help, and revealed his suicidal plan to them. Hazel and Frank were shocked, with a tear falling down Hazel's cheek. Leo said it had to be this way, and Apollo and Nike confirmed that. He said he couldn't tell the others, since they wouldn't accept it, but he knew Hazel and Frank would understand because they were Romans, knowing about sacrifice. Leo said that he was counting on Frank to make the call no one can make, and that Hazel's whole life with Sammy was leading up to it. They both started crying and hugged Leo. They agreed to do the plan, but said they despised it.
The next day, Leo went with Piper and Jason to Epidaurus to meet Asclepius and get the cure. Frank hugged him before he left, saying to be careful. The three defeated an automation of Hygieia, the goddess of hygiene and good health, by using idiot mode. He then reprogrammed the sign to the doctors office to be let in. When they got let in, Leo told him about the cure, and he knew that Leo would sacrifice himself, giving him a sad look, which Piper and Jason noticed. Leo reassured them that he was fine, but Piper and Jason were suspicious. They then got the cure and left. Jason knew the way he looked at Leo was off, but Leo convinced him it was nothing, and he just was excited to see Calypso. But Piper didn't believe him. That night, Leo ate dinner with the seven, and Hazel and Frank glanced at Leo when they discussed who will die. Leo ended up choosing Piper to hold the cure, and had Hazel give her a fake mist version of it. Piper and Jason tried to talk to Leo about Asclepius yet again, but he evaded them. Then, Leo went to work in the engine. He injected the cure into Festus and checked the astrolabe that would go to Ogygia. He told Festus they'd be together to the end and swore on the Styx that he would find Calypso. He then set a timer for 24 hours for the cure to be given.
The next morning, Leo met Kekrops with everyone. Leo briefly argued with Percy about zodiac signs, saying he was a Leo and Percy was a Percy, after Percy said his sign was a Leo. He also had a piece of bundt cake before Piper could warn him it may be poisoned. Leo was very impressed at Piper's singing, and said it was beautiful. Annabeth then pulled Leo, Hazel, and Frank over to talk strategy. Leo ended up helping lead a charge into the Parthenon with Hazel, Frank, and Jason. Leo flew the ship above the ruins and equipped it with ballistae and catapults, which were fired simultaneously, incinerating the smaller monsters. He yelled on a loudspeaker, saying to surrender to spanking hot war machines. However, he was defeated by Enceladus after he threw his dagger at the ship, making it fall from the sky. But he ended up helping defeat giants when his father, Hephaestus, arrived. Leo ran across the deck, shooting at the giants and dropping fiery hammers on the giants, while Hephaestus took control of the ship, trying to keep it afloat. Leo then discussed with the gods what to do to defeat Gaea. Leo helped convince them to throw the Argo II to long island. Nike also alluded to Leo sacrificing himself, worrying Annabeth, and filling Jason with dread.
When they arrived back at Camp Half-Blood, Leo ordered them all to get off the ship. Jason and Piper tried to get him out, but he reassured them that he had a plan. Jason and Nico were very worried for Leo and charged into battle "For Leo". Leo ended up turning the Argo II into Festus and flying to Jason and Piper's aid as soon as Gaea rose, picking up Gaea with Festus's claws. Will and Nico were surprised when Leo rose, but Will said they had other things to worry about. Leo flew on Festus, with both of them blowtorching Gaea, saying this was for his mother, and hurling insults at the primordial deity. His whole body was on fire. After Gaea blacked out from Piper's Charmspeak, Leo told Piper and Jason to go. They insisted to stay, since Piper had the cure, but Leo said he had a plan and to trust them. The last thing he said was that he loved them before dropping them from Festus's claws. Festus and Leo became a ball of fire. They were then intercepted by Octavian, tangled in his onager, hurtling towards them, which Nico let happen, knowing some deaths couldn't be prevented. The explosion turned the sky gold.
In the aftermath of Leo's death, the Hephaestus cabin searched for Leo and Festus, but couldn't find him. Nico and the rest of the seven then met up at the big house, where Hazel and Frank revealed their part in Leo's sacrifice. Everyone but Nico was originally mad at them, but they realized it was an annoying, heroic, and noble plan Leo would've done. Nico honored the dead, including Leo, and felt very guilty for his death, blaming himself. Hazel also did, sobbing about how he died alone. Even though Nico told Jason and Piper that he felt his death, they were hopeful he was still alive and spent a night talking about him, honoring his memory. Percy and Annabeth were also hopeful he was alive. 
Leo's death hurt very much, and he woke up with a lurch after Festus gave him the cure. He said that being dead sucked and thanked Festus for saving him. He couldn't remember what exactly happened, and didn't know that Octavian played a part in his death. Leo then realized the navigation was screwed up, and Ogygia was near. They flew down to the island and saw Calypso waiting on the shore. He fell face first in the sand, since his leg was broken. Calypso said he was late, and Leo apologized, saying there was bad traffic. She then complained that he ruined the clothes she gave him, wrinkled her nose by his smell. Leo explained that he died, but he was interrupted when she kissed him. Leo saw that Calypso was ready to leave the island, and questioned if she would stay immortal once she left. She admitted that she wasn't sure, but she was more than okay with it. Leo gathered her bags and they flew into the unknown on Festus, with her arms around his waist. 
==Between the Series==
Several days after the deaths of Gaea and Leo, a parchment scroll with a holographic message, sent from the resurrected Leo, came fluttering into Camp Half-Blood on the wind. Leo recorded the message while flying on Festus' back, and in it, he reveals that he has managed to get resurrected and find Calypso, and apologizes for leaving his friends and fellow campers in such a manner. However, the message is not of perfect quality, so the latter portions of it are filled with static. He ends the message by stating that he loves them all, and cheerfully asking for tacos to be cooked for his arrival. The scroll is later kept by Nico di Angelo, who takes to looking at it every time he begins to get angry at Leo.
Leo later mentions that during his long journey back to Camp Half-Blood with Festus and Calypso, he had flown through the Sea of Monsters (encountering Polyphemus along the way), and had an embarrassing experience in Albania (with Nico hastily shutting Leo up before the latter can get into the details).
==The Trials of Apollo==
===The Hidden Oracle===
Six months after Gaea's 'death', Leo, Calypso, and Festus finally return to Camp Half-Blood after the camp is almost destroyed by the Colossus Neronis. The campers take numbers from Nico di Angelo, so they could both welcome Leo back and punch him, as well as a few campers he never met and Chiron (with Nico himself being the last one to do so). After some discussion, Leo and Calypso decide to go on the quest with the former god Apollo. He was given extreme love and anger and was keen on finding Jason and Piper. 
===The Dark Prophecy===
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Leo, along with Apollo and Calypso, lands in Indianapolis. He stops Festus from burning the state flag on the capital building. He asks Apollo if he senses Meg or the Oracle, but he does not. He notices Festus is functioning strangely and sets him on the ground before turning the dragon off, but not before his clothing is burned off leaving Leo in his underwear in public. He says they if they can find a machine shop, they can leave in about half a day. They are approached by a woman named Nanette who identifies and grabs Apollo. When Calypso frees the former god, she goes to check up on his wounded girlfriend. The woman is then revealed to be a Blemmyae working for Triumvirate Holdings, who then calls for back up. He helps Calypso again after she breaks her ankle kicking Nanette. He tries to go back for Festus, but Apollo tells him they would be captured if they do so. They head to an alley where a headless ghost tells them to go somewhere. They are soon cornered by their headless hunters. Leo asks Apollo and Calypso to distract the blemmyae while he heads softly for the bulldozer the headless foes brought with them. He reaches the bulldozer and blinds the driver. The three try to get away, but Nanette catches up to them. Leo throws a fireball at her, but she eats it. Before anything can happen to them, Nanette is killed by an arrow. They see a woman who takes out all the blemmyae. She introduces herself as Emmie and tells them to come with her to the Waystation.
They arrive, and as Emmie takes Calypso to the infirmary, she tells them to head to Josephine. They meet up with the other woman, whom he almost immediately bonds with over a shared love of machinery. She explains who founded the Waystation and what it is used for before going back to her wielding and telling her guests to make themselves at home. He goes to talk with Josephine when Apollo passes out while having a vision. He and the others watch over him during this time. The trio learns that Emmie and Josephine's adoptive daughter, Georgie, has been taken by Triumvirate Holdings. They also find out that he fits into an eight-year-old's clothes, much to Josephine's amusement. The five prepare and eat lunch while Josephine and Emmie explain the condition of the cave of Trophonius and their abducted guests. They hear a banging coming from the roof. The ex-hunters go to investigate while Leo and the others stay put. The three do the dishes while Apollo tells the ritual to gain a prophecy from Trophious. Leo suggests he reprogram Festus, but Calypso scolds him for think technology can fix everything. They then find Apollo trapped in a net by the net goddess Britomartis. The goddess tells the trio of the emperor's plan to rename the city and kill Apollo and Georgina in three days. He disarms her traps during the conversation. She sends Apollo, Andy, and Calypso to the city zoo to free her griffins and tells Leo to say and work on the Waystation's defenses. After they tell the ex-hunters what Britomartis told them, they have their guests do chores with Leo cleaning out the griffin's nest. They eat dinner and send him and Apollo to a separate wing from Calypso. Leo tells Apollo that he feels Calypso sometimes blames him for her lack of powers at times before going to bed. He is left asleep while his companions leave to free the griffins at the zoo.
He and Josephine get Calypso to the infirmary after she returns from freeing the griffins. He is enraged at the net goddess for channeling her power through Calypso. Josephine calms him down before Britomartis gives them the information they want. He is told to go with Apollo and Meg McCaffrey to the river to find a back entrance into Commodus's palace. When learning that Lityerses will be there, he eagerly agrees to go. After the goddess leaves, Meg says the god-emperor's name while Leo and the others tell her to stop.
The next day he, Apollo, and Meg head to Canal walk and take a pedal boat down the river. He asks Apollo why he was so quiet and understood why he drowned Commodus. The trio sees a monster under the river and proceeds with caution. They find the entrance, but they are attacked by the Carthaginian Serpent. He tries to open the gate while Apollo and Meg fend off the serpent. He opens the door and they slay the serpent and head into Commodus's lair. They wade until they see an alcove to dry off on before continuing. He opens a second door while Apollo and Meg stand watch. They enter and find Commodus planning to attack the Waystation by the next morning. After the god-emperor leaves, the three devise a plan of action. They locate the prison, and he and Meg take out the guard. He then opens the door. He melts the Plexiglas of the cells, letting the prisoners go free. He takes the prisoners and Festus back to the Waystation while Apollo and Meg find the Throne of Memory. Leo flies in on Festus as part of the reinforcements along with the Hunters of Artemis. He reluctantly takes Lityerses with him when retreating.
He was working on Festus when Apollo returned and headed the message. After he pointed out the part about Commodus, Literyses says Commodus put a tracer on the griffins and is going to destroy the Waystation the next morning. He and Josephine have been working on the Waystation's defenses in preparation for the battle. After talking with Emmie and Josephine, he and Calypso decided they want to stay at the Waystation and live normal lives. 
He set up mines to stop bulldozers before the battle but was taken hostage by Commodus along with Emmie and Georgie. He looks to Apollo to see if he has a plan when the mortal god goes into his Divine Form and blinds the emperor, he helps Emmie and Georgie getaway. After the battle he and Josephine rebuilt Festus.
During dinner, he volunteers to fly on Festus to Camp Jupiter to warn them of their impending attack. He reassures Calypso that he will be back in time for the spring semester. The next morning he is arguing with her about what to pack.
===Warning Camp Jupiter===
Leo makes it to Camp Jupiter twenty-four hours in advance and warns them about the attack. After the legion takes numbers to punch and hug the son of Hephaestus, they use his semi-advanced warning to prepare for the attack. He and Festus burn the undead forces of Tarquin and help the legion gain a narrow victory.
===The Burning Maze===
He and Festus arrive at an airfield in Santa Monica but is distraught over Jason’s death, wishing he could have seen Jason one last time. He then discusses what happened during the attack on Camp Jupiter. He says the Twelfth Legion Fulminata managed to ward off the attack, however, there were many casualties (minus Frank, Reyna, and Hazel) and the camp is in ruins. Leo insists on taking Piper McLean to Oklahoma on his way back to Indiana.
=== The Tyrant's Tomb ===
Frank Zhang mentions how Leo's warning gave them a slight advantage over the attack, and that the legion took numbers to stand in line and punch him.
===The Tower of Nero===
After becoming a god again, Apollo visits the Waystation where Leo has just returned from a day of doing community service teaching homeless kids at a shelter shop skills. Leo compares the kids to himself, stating that they've never had much and he can at least show them that somebody cares. Leo is also pleased that some of them are excellent mechanics. Apollo questions if Leo wouldn't need a shop or tools, but Leo explains that he has Festus who makes a great mobile shop. Also, while most of the kids only see the bronze dragon as a truck due to the Mist, some of them are capable of seeing his true form. Passing by, Jo comments that Leo is doing good and he has a lot of potential.
Apollo asks about Calypso, causing a flurry of emotions to pass over his face, causing Apollo to realize that Leo is more lovesick than ever and that things are still complicated with Calypso. Leo states that Calypso is enjoying going to high school and is currently working as a counselor at a mortal band camp for the summer. Apollo notices that Leo is clearly worried, clearly missing her and possibly having nightmares about all the hot clarinet player counselors that Calypso might be hanging out with. With a forced smile, Leo states that its all good and that they'll make it work, suggesting that a little time apart to think might be good for them. Passing by, Reyna tells Apollo that she'd had to have a heart-to-heart with Leo and teach him about respecting women more. Reyna states that Leo grew up without a mom and as such, never learned these things, but he now has two foster moms and a big sister who isn't afraid to smack him if he gets out of line. Seeing how glum he still is, Reyna reassures Leo that Calypso will come around because Leo is a doofus sometimes, but he has a heart of Imperial gold.
==Percy Jackson's Greek Heroes==
While narrating the adventures of Theseus in this book, time after Leo's return in The Hidden Oracle. Hence, Leo is therefore most likely attending the monthly Argo II reunion party that Percy is worried about being late to. Percy also said that since in Pallene, the people couldn't stand the name Leo, Leo would probably go over there and introduce himself fifty times a day just to see how people would react.
==Personality==
Leo is mischievous, flirty, upbeat, resourceful, eccentric, and impulsive, and loves to tell jokes constantly, even if they aren't particularly funny. He prides himself on being the 'class clown' and pulling pranks on those around him. Leo is genuinely very intelligent and honest and cares about his friends and found family. Being bullied growing up taught him to adapt and entertain even under pressure, as making his enemies or peers laugh prevented them from attacking him. He is also shown to be incredibly brave and selfless, willing to sacrifice himself to save his friends and stop Gaea. He is said to be sensitive about his size and occasionally makes self-deprecating jokes about it. Even with his mischievous personality, Leo is also a leader, as he is the counselor of the Hephaestus cabin and a commander on the Argo II.
Despite his easygoing attitude, Leo is emotionally scarred from the death of his mother as he blamed himself for most of his life for causing her death. He hid a hurt and angry demeanor with humor until realizing that his mother's death was not his fault. Leo's serious side exhibits when he is angered by someone, when those he loves are threatened, or when the situation calls for it. He is also frequently seen building small machines and gadgets, and is very skilled and serious about his work, having built a large portion of the Argo II on his own. He is able to funnel his nervous energy into mechanical solutions to seemingly insurmountable problems. Leo has a tendency to view even the most emotionally-charged situations objectively, which Calypso disapproves of. This causes conflict between the two. He also feels that his whole life has been nonstop danger and running, which is reflected in his abundance of nervous energy and need to always fidget and keep his hands moving. 
He is known to fall in love with any beautiful girl as long as she is completely out of his league, such as in the case of Khione and Thalia. For example, when Thalia, Jason, and Leo were in the cave alone, Leo asked Thalia if her no-dating policy was seasonal, but she ignored him. Khione, being a snow goddess, hated Leo, as she could sense the fire within him. She took his compliments (Leo once called her hot) as insults. He regularly describes himself as bad at talking to girls and more nervous when he is around them. Being "bad with organic lifeforms" may come from his father, Hephaestus, who once described himself as such. 
Near the end of The Lost Hero, he starts to let go of the pain of his mother's death and learns that his pyrokinesis is a gift and tool, not a curse. He also decides to stop running from his past and he starts opening up to his friends more. As of The House of Hades, after visiting Calypso for the first time, Leo became more steady and yet heartbroken, but he still made jokes, albeit less frequently. Facing heartbreak from this experience seemed to age him somewhat, often seeming sad and far off, thinking of Calypso and his promise to her. Leo's maturation after meeting Calypso is quite typical of someone who experiences heartbreak after a lifetime of feeling like an outcast. 
===Fatal Flaw===
While Leo's fatal flaw has not been revealed, he shows feelings of inferiority - being unwanted or not trusted, the one no one wanted. He also can say the wrong things at the wrong time, as shown in The Dark Prophecy when he is held captured by one of Commodus' men, a Germanus named Albatrix.
==Appearance==
In The Lost Hero, Leo is described by Jason to look like a "Latino Santa's elf," with curly black hair, dark brown eyes, pointy ears, a cheerful, elf-like face, normally with a mischievous and impish smile, and a diminutive stature with a slim and relatively scrawny build. He is implied to be fairly short, between Piper and Hazel in stature. Leo's most notable trait is that he has a look in his eyes that makes him look not only like a troublemaker, but also like he has taken much more caffeine than the normal limit; this could be linked to his ADHD, although he is described as being seriously ADHD even by demigod standards, according to Annabeth. Although not being quite as handsome as Jason, Percy, and Frank have been described, Leo has been called 'cute in a scrawny way' by nymphs and the Maenads from Demigod Diaries, indicating that Leo is quite good-looking despite not finding himself attractive. His upbeat attitude and humor also contribute to his charisma.
During The House of Hades, Hazel noted Leo's curly hair had gotten longer and shaggier, and his face got leaner, so he looked less like an imp and more like 'one of those willowy elves in fairy tales". His eyes also constantly drifted, as if he was trying to spot something over the horizon.
In The Trials of Apollo, Leo is described by Apollo to be diminutive and unimposing. In The Dark Prophecy, Leo wears a pair of Georgina's overalls during her absence, so they are probably around the same size.
==Abilities and Tools==
<tabber>General Abilities=
As a member of the Seven and a son of Hephaestus, Leo is extremely powerful and had displayed excellent battle skills even without formal training.
*ADHD: Like most demigods, Leo possesses inborn supernatural battle reflexes and senses that he uses to analyze the fighting style of his opponent. According to Annabeth Chase, however, Leo is seriously ADHD, even for a demigod. 
*Dyslexia: Leo's brain is hard-wired for reading Ancient Greek instead of modern languages.
*Morse Code: Leo's mother taught him Morse code, a skill he has retained, and he was therefore able to understand Festus' last wish. As of The Blood of Olympus, Leo and Annabeth are the only known demigods to know Morse code. 
*Trilingual: Leo can speak Spanish, Greek, and English fluently, having learned both English and Spanish from his mother as a child, and knowing Greek naturally because of being a demigod.
*Genius Intellect: Leo is very intelligent. He had learned to think three-dimensionally, and solve mechanical problems in his head. Even at the age of eight, he can do math better than most adults. He is very clever and witty, and is good at adapting, letting him build at any circumstance. He had used his wits, which helped him survived in tough schools and neighborhoods, and a master problem-solver.
*Superhuman Strength : Being a demigod, Leo is stronger than a regular mortal. However, Leo has many times labeled himself as weak because of his small stature, and is definitely the weakest male demigod of the Seven, indicating that Leo is pretty weak for a demigod. Leo also is extremely skinny and short and doesn't look very strong. However, Leo has been shown to be quite a bit stronger than he looks as he used two silver-tipped blacksmith hammers to smash full-grown monsters that got in his way.
*Superhuman Agility: Being a demigod, Leo is more agile than a regular mortal as he was able to twist his body in mid-air to hang on to a ledge of a cliff after flung off. He was even able to easily launch himself in a backwards somersault to avoid getting crushed by rocks thrown by the Earthborn.
*Superhuman Durability: Being a demigod, Leo is more durable than a regular mortal as he shook off falling from dozens of feet, shake off crashing to Calypso's island from a high distance, able to survive crashing face first in the ocean from dozens of feet, and many feats. In The Lost Hero, when Piper, Jason, and him fell from the sky, crashed into a ceiling, and slamming on a metal catwalk, he and Jason was able to walk away from it with no signs of discomfort.
*Cooking Skills: As shown in The Lost Hero, Leo is an amazing cook.
*Superhuman Reflexes: Being a demigod, Leo's reflexes are faster than a regular human. Leo was able to dodge thrown projectiles by the Cyclopes, dodge rocks thrown from the Earthborn, and was quickly able to jump off from a helicopter before it got crushed. He was even close to catching a mechanical snake in The Blood of Olympus. The explanation of why Leo is so fast could be because he's very ADHD even for a demigod.
*Fighting skills (Limited): Despite receiving no known formal combat training, during the battle at the Wolf House in The Lost Hero, Leo displayed considerable combat skills by using two silver-tipped blacksmith's hammers to "smash any monsters that got in his way," even while fighting Khione, the ice goddess at the same time.
|-|Demigod Abilities=
*Technokinesis: Leo has amazing mechanical abilities even for a child of Hephaestus; he can manipulate a megaphone to say "The cow says moo" in a low voice like Darth Vader's and build a working helicopter out of pipe cleaners. He was able to fix the mechanical dragon Festus in one night, even though the rest of the Hephaestus cabin thought it was beyond repair and had to be destroyed. He even added wings to the dragon so it could fly. After Festus was destroyed, Leo initially believed that he had no chance of rebuilding him, but did so in The Blood of Olympus in secret over the course of several weeks. In The Dark Prophecy, Leo is revealed to have redesigned the dragon so that he can be easily rebuild in the event of another such destruction and indeed has him mostly rebuilt by dinnertime. In The Blood of Olympus, his father Hephaestus acknowledges Leo's mechanical skills and compliments him on the creation of the Argo II.
**Machine Aptitude: Leo can understand and sense machinery and has the ability to expertly operate machines he has had no prior experience with. He can also communicate with machines such as Festus.
**Machine Expertise: Because Leo is a demigod child of Hephaestus, he can instinctively fly or drive any mechanical vehicle expertly, including trains, or helicopters. He can drive cars too, although it makes him carsick, as shown in The Mark of Athena.
**Machine Sensitivity: He can sense faults in metal ore and identify machinery type and use by touch.
*Trap Detection: Leo can also sense traps, in particular mechanical traps, shown when he saw the hidden trap meant to catch Festus in The Lost Hero, and when he knew where all the defense mechanisms were in Midas's yard and disarmed them remotely.
*Pyrokinesis: He is the first demigod child of Hephaestus in hundreds of years to master the ability of pyrokinesis, the ability to generate and control fire. At low-level ability would probably be moving a candle back and forth; if better, maybe putting out the flame with his mind or making it relight. Pyrokinesis is one of the more practiced skills like telekinesis. It is too, for warming people up or setting objects aflame. His pyrokinesis is supposedly a curse, but he is determined to interpret it as a gift. His pyrokinetic abilities can go as far as to shoot white hot flames high in the air that could burn through a metal chain link, and by causing powerful explosions from impact from his fireballs. He was able to easily keep the upper hand against the snow goddess Khione for an extended period of time forcing her to go on the defensive, eventually forcing her to flee. An impressive feat given that fighting a god/goddess is "suicide," this is made even more impressive by the way Leo was going to completely overpower Khione and this could show Leo's power is comparable to that of a child of the Big Three. Jason had even noted that Leo was the only reason why they were still alive, since the heat from his fire was able to melt almost all the ice from the Wolf House. However, sometimes he has trouble controlling his pyrokinesis when he gets excited or scared, beginning to heat up and smoke. He can throw fireballs/fire bolts, fire blasts and (if he concentrates hard enough), columns of fire. However, this ability had no effect on the Gigantes Clytius. In his most powerful display of pyrokinesis, Leo was able to scatter Gaea herself.
**Superheated Fire: Leo can increase the heat of his fire to the point that it becomes white-hot, and can also create walls of flame. This is the main defensive use of his powers.
**Supernova: Leo can increase the heat of his fire to such an extent that he basically becomes like a supernova. He was able to use this ability to defeat Gaea in The Blood of Olympus, but the side-effects effects of using his power in such a way were fatal to him, enough to char his otherwise fireproof body, despite his immunity to flames. It is possible this is survivable now, because as his fire usage and immunity are strained, they get stronger. However, Leo has not attempted to use this particular aspect of his powers again since his resurrection.
**Fire Immunity: Leo discovers that he is fireproof and he can even survive a kerosene barrel explosion without feeling any pain in The Lost Hero, unlike Jason who feels the pain of heat but is unharmed by lightning. For example, when he was a small baby, Hera, in the form of Tia Callida, his "insane" babysitter, puts him in a blazing fireplace and he is completely comfortable. However, when he was attacked by Festus's firebreath, it did sting him slightly. Many other things like this follow. However, Leo's supernova fire explosion combined with Octavian's onager projectile in The Blood of Olympus was fatal even to Leo, enough to char his body. 
**Heat Sensitivity: He can sense heat and flames, even allow him to walk through the forest at Camp half Blood at night in The Lost Hero, in the form of thermal vision.
|-|Magical Items=
*Magical Toolbelt - He has a magical tool belt that he uses constantly. He can pull simple tools from the belt, as well as food, medical supplies, and breath mints. The belt is seemingly endless and he doesn't know where it all comes from. However, larger items, especially things that don't have to do with mechanics, require the belt to recharge or "cool down." It is also known that big items, such as chain-saws, or magic items, like Jason's sword, Ivlivs, cannot be pulled out of the belt.
*Hammer - His primary weapon is his 3-pound club hammer, which he summons from his tool belt from time to time.
*Festus the Bronze Dragon - Was repaired and managed by Leo after his discovery of Bunker 9, used in the American Civil war as the Hephaestus bunker. He supported Leo, Jason, and Piper, all the way to Midas's mansion, where he was destroyed by lasers to save Leo, Piper, and Jason. He was later used as the masthead of the Argo II. By the end of The Blood of Olympus, Leo has secretly rebuilt Festus, building him a new body in the Argo II. After Leo sacrifices himself to stop Gaea, Festus brings him back using the Physician's Cure. Festus continues to serve Leo who designs the dragon to be easily rebuilt before the events of The Dark Prophecy. When Leo begins teaching mortal kids in The Tower of Nero, Festus acts as his mobile workshop.
*Holographic Scroll - Leo's own invention, used in The Son of Neptune to alert Camp Jupiter that the Argo II is coming. A few days after his death and resurrection, Leo used another one to send a message to his friends at Camp Half-Blood.
*Buford - Leo's magical three legged table.
*Archimedes Sphere - Leo found it in Archimedes's workshop and repaired it. After that he upgraded the sphere an made several copies. He can use it in different ways.
*Odysseus' Astrolabe - An astrolabe created by Odysseus to rediscover Ogygia. Leo claimed it as a spoil of war from the Kerkopes and later received the crystal that he needed to complete it from Calypso. When Leo rebuilt Festus, he installed the astrolabe in the bronze dragon who was able to use it to find Ogygia so that Leo could rescue Calypso.
*Physician's Cure - An ancient healing potion that can bring back the dead. The Seven put it together as part of their plan to defeat Gaea and Leo gave it to Festus who used it to resurrect him after Gaea's defeat.
</tabber>
==Relationships==
=== Love Interests ===
<tabber>
Calypso= 
In The House of Hades, Leo lands on Calypso's island, as the gods had not seen to Percy's wish of setting her free from Ogygia, her cursed home. Although Leo and Calypso do not get along very well when they first meet, when he works to escape, she turns out to be a great help and they become friends. They also share a kiss just before Leo leaves. Leaving Ogygia, Leo doubts that he really is "in love with an immortal girl" and that Calypso is in love with him. He then swears upon the River Styx that he will come back for Calypso. When he returns to the world, it is clear that he misses Calypso: Jason notices that he has lost most of his nervous energy and has the same heartbroken expression that he saw on Nico.
In The Blood of Olympus, Leo is obsessed with returning to Calypso after he has defeated Gaea. Once Gaea is gone, he returns to Ogygia and takes Calypso back into the mortal world.
In The Trials of Apollo, the two are in a romantic relationship but have some rocky moments. In The Tower of Nero, the two are going through a rough patch, but both Leo and Reyna are confident that Leo and Calypso will work it out.
|-|Khione= 
thumb|right|175px|Khione, his former love interest.
When first meeting Khione, Leo states he acted like a total fool, but couldn't help it. While Jason and Piper where upstairs talking to Boreas, Leo had his clothes cleaned, his hair brushed, and took a pack of breath mints from his toolbelt in hopes of impressing her, but ultimately failed.
When meeting Khione again at the Wolf House, Khione tried to use Leo's attraction to her against him. Saying that he could join her and become her champion, instead of following the path the Fates had given him. Leo on the other hand rejects her because of what she had done to Festus and comments that he can't believe he thought she was hot, something Khione, the snow goddess, takes great offense to.
|-|Echo=
Echo is a nymph that Leo met while on an island in the Great Salt Lake. While Leo originally teases her, as she is forced to repeat the last thing she hears, he stops after Hazel Levesque tells him to stop (as well as Echo turning his words against him). After meeting Narcissus and seeing how absorbed he is in himself, as well as all the nymphs loving him for his looks, he realizes that Echo is the only one that truly loves him for him and wants to save him. Echo helps Leo in his plan to steal a metal shield Narcissus is using as a mirror and aids in Leo's escape. While running away, she plans to fight off the nymphs that are after them. Leo sees her true face for only a minute and offers to bring her with them, but she refuses as she still loves Narcissus.
</tabber>
===Friends===
<tabber>
|-|Jason Grace=
Though Leo and Jason first met in The Lost Hero, Leo had fake mist memories of being his best friend at the Wilderness School. Leo remembered messing with Jason, pranking him, and in return, Jason wouldn't be annoyed by Leo's jokes. However, when Jason and Piper started dating in the fake memories, Leo felt like he was not needed anymore and even though he was happy for them, he felt like a third wheel. When the two actually met, Leo thought that Jason was messing with him and faking his amnesia to get back at the last time he pranked him. But Jason knew that he never met him before and that his memories were fake. Leo tried to mess with Jason, saying that he does everything he says, does his chores, and gives him dessert, but Piper chastised him. Jason thought that Leo was weird, and told him that. He thought that if Leo was his best friend, his life must be very messed up. Jason tried to question Leo to see if they were really friends, and when Leo couldn't prove the details of when they met, Jason knew that he was right. Nevertheless, Jason was concerned about Leo's safety when he was attacked by Dylan.
During the campfire that night, Leo volunteered to go on the Quest for Hera with Jason, saying that he can get him a ride. Jason smiled and let him go, saying that since their journey started together, it was right for him to come with them, and that if he can get him a ride, he can go. Leo was overjoyed and pumped his fist. Leo knew that he could help Jason as soon as he heard his vision, and knew the woman he saw was the same woman who he saw as Tía Callida. Leo ended up fixing Festus to transport Jason and Piper on the quest. Jason was weirded out but amazed when he found out that Leo fixed Festus, and thought it was weird that he named it Happy the dragon, but was ready to accompany him.
Leo and Jason bonded over the course of the quest when Leo saved Jason from Ma Gasket and the other cyclops, and trusted Jason enough to tell him about Tía Callida, still considering Jason his friend. Jason was very impressed with Leo when he saved him from the cyclops with one tool kit, thinking it wasn't bad. In return, Leo was also grateful for Jason when he was willing to fight Calais and Zethes to save him. In Chicago, Leo even confided in Jason, telling him about his fire powers and his mother's death. Jason was very Impressed by his cooking and his fire powers, and when Leo said he didn't want to tell him because he didn't want to look like a freak, he reassured him that he was just as a freak as he and Piper were. He also reassured him what happened to his mom wasn't his fault. 
However, on the quest, Jason and Leo developed a slight rivalry. Leo was jealous of Jason and Piper, and hated that they left him out of things when they were talking. He was jealous that they got to meet Boreas and not him, while he had to deal with Calais and Zethes. Their rivalry finally came to a head when they were charmspeaked to fight each other by Medea, telling them that they resented each other. Leo revealed that he thought Jason was always the star, who took everything for granted, and Jason said that Leo was annoying, who cannot take anything seriously or even fix a dragon. Piper managed to snap the two out of it and save them from killing each other. After the incident, Leo and Jason both felt horrible about how Medea turned them against each other, and Leo felt bad about how he did secretly resent Jason for the things he told him. Leo was upset about what Jason told him, even the next day, made worse by the fact that Festus broke for good. Jason tried to apologize, and said what happened wasn't Leo's fault and reassured him that he was amazing, but Leo brushed it off, still upset by his failure. Jason finally apologized in Omaha, saying he didn't mean anything he said and that he wished he could do half of the things Leo could do. He said that Leo did take things seriously and that he wasn't annoying. Leo accepted his apology, and joked that he can't resent him if he apologizes, and that he is supposed to. He told him that he is annoying and to not insult his ability to annoy. This eased the tension between the two.
Jason and Leo bonded even more afterword, and Jason even wanted Leo there with him when he talked to his sister, Thalia Grace. Leo was very surprised when Jason wanted him as support, and Leo said that sticking around was his specialty. Jason also told Thalia to not mind his jokes. For once, Leo didn't feel jealous of Jason and actually sympathized with him, knowing that he was lucky to know his mom while Jason didn't, finding himself saying "Love You" in Morse code on his knee. Later, when they went to Aeolus's palace, Leo went to comfort Jason while they walked, and Jason expressed his jealousy towards Thalia of having all the demigod stuff together. Jason even confided in him, saying he wondered if what happened with his mom was his fault. Leo supported him, saying that it takes awhile to get used to demigod stuff and that what happened with his mom wasn't his fault. The next day, when Piper was worried that Jason would betray them, Leo knew that he wouldn't and trusted him as part of the team. Jason was amazed when Leo showed him Bunker 9 back at Camp Jupiter.
By The Demigod Diaries, the two were best friends. Jason helped Leo calm down when he made a huge mistake with Buford, and went to Bunker 9 with Piper, ready to help. Leo thought of Jason as cool, confident, and surfer dude handsome. Jason was very confused, but Jason was determined to help his friend. After they saved Camp, Jason sat with Leo and Piper at the campfire and they drank hot chocolate. Leo thanked Jason for saving him, and Jason reassured Leo that he would do anything for him. The three all did a toast to each other, to friends. During the ensuing months at camp, Jason and Leo would play the Wii, with a program Leo made called "idiot mode". 
In The Mark of Athena, Leo was very concerned for Jason after he was injured by the Romans. Leo considered Jason his best friend and didn't know what to do with himself if Jason didn't make it. And when Percy and Annabeth came to check on Leo, he immediately asked if Jason was okay. Leo felt extremely guilty for what happened and blamed himself. However, Leo felt insecure about being the third wheel with the two, not being included as much when Jason and Piper had "quality time" together, making Leo feel like an outsider. But this didn't affect his friendship with Jason at all and didn't resent him for it. Leo was ecstatic after he returned from Salt Lake City to find Jason awake, and greeted him, saying he was glad he was better. Jason reassured Leo that what happened was not his fault, not blaming him for his injury. Leo and Jason also agreed with each other that they were not sure if they could trust Nico di Angelo, and Jason defended Leo when Hazel almost yelled at him. Leo and Jason collaborated numerous times on the way to Rome, including raiding a Confederate museum with Frank. Jason was extremely worried when Leo went missing, and flew around the Atlantic Ocean like a madman trying to locate him. At the end of the book, Jason clapped Leo on the shoulder, calling him the admiral.
In The House of Hades, Leo empathized with Jason having to be the sole leader of the Argo II, and Leo could tell how stressed out his friend was. He could tell that he had sunken eyes and uncharacteristically messy hair. He knew Jason was most likely used to being under stressed from being Praetor at Camp Jupiter, but still felt bad for him. Leo trusted Jason's abilities as a leader, and thought he had a talent for being levelheaded in a crisis, getting Leo out of bad situations. As for Jason, he was close enough to reprimand him when he went too far, especially when making jokes at Nico's expense. Jason was very confident in Leo's abilities, and was certain that he would be able to defeat Clytius due to his fire powers. He also knew that Leo could always light things up when the team was down. Leo and Jason collaborated on defeating Akmon and Passalos, and Jason flew Leo around Bologna in order to catch them. 
When Leo was blown off the Argo II by Khione, Jason was devastated from losing his friend, and was guilty that he was rendered helpless while Leo was blown off the ship. For five days, Jason confronted Auster and Notus to try to convince him to help him find Leo. Jason was extremely worried about Leo and thought he was in trouble and lost. On the fifth day, when he met with Auster, he asked him yet again to give him news about Leo, and begged him to let them leave and tell him where Leo is so they can head on to Epirus. During the conversation, Jason realized that his months with Leo at Camp Half-Blood were more fulfilling than his lives at Camp Jupiter, and that he wanted to stay with him at Camp. Jason was overjoyed when he reunited with Leo at Malta, but could tell that his friend was heartsick, just like Nico in Croatia. He could feel that he no longer had nervous energy and it was replaced by a wistful sadness. Jason squeezed his shoulder and asked him what happened, but Leo refused to elaborate. Jason knew that something happened between him and Calypso, but knew he didn’t want to talk about it and changed the subject.
In The Blood of Olympus, Leo loved all of his friends, including Jason, and would do anything for them. Leo was very worried about Jason when he was injured at Ithaca. Leo could hear the pain in Jason's voice and wanted him to rest, worried that he would die from the imperial gold. He even felt helpless about Jason's state, knowing that people are harder to fix than metal automations. Leo also regarded Jason as the least likely to slap him when he made bad jokes, which is why he sat next to him at breakfast one day. As for Jason, he wished Leo wasn't so protective of him after his injury, and wanted to prove himself to the team. Leo was very worried when Jason went up from below deck to help everyone, telling him to go back downstairs. Leo and Jason later went to Epidaurus with Piper to meet Asclepius, where Leo hid his suicidal plan from him. Jason questioned him about it after, but Leo refused to tell him. In fact, one of the reasons Leo did what he did was to save Jason, knowing it was one of them that would die.
Once they made it back to Camp, Leo stayed on the ship and told a Jason to go. He felt bad about leaving him behind, but he knew that just like when he met Zeus, there was no time for a proper goodbye to his friend. Jason almost cried to Nico telling him where Jason was. They both thought he would be okay, but they charged into battle "For Leo". Leo ended up seeing Jason for one last time when he flew down with a repaired Festus, and Jason, Piper, and Leo helped defeat Gaea together. When Gaea passed out, Leo urged Jason and Piper to go, and Jason refused, saying Piper had the cure and that they needed to stay with him. Leo told them he loved them as he dropped them to the ground, the last words Leo would ever say to Jason. In the aftermath of Leo's death, Jason was initially furious at Hazel and Frank for keeping Leo's suicidal plan from him, but he knew that was a plan Leo would've done. Even though Nico told him that Leo was dead, Jason chose to believe that Leo was still alive and told Piper so. The two then spent the night talking about the memories of their friend. 
In September, after Jason and Piper received a parchment scroll from Leo, they spent the entire month looking for him, until Chiron urged them to get on with their education. Jason still hoped during those months that Leo was still alive. As for Leo, in both The Hidden Oracle and The Dark Prophecy, he expressed interest in seeing Jason again. 
In The Burning Maze, Jason found out that Leo was alive from Apollo. Jason was so shocked all of the electrical outlets in his dorm room sparked, and he looked at Piper, stunned. He said he didn't know whether to laugh or yell, after all he'd been through grieving for him. However, Jason never got to see Leo again because he was killed by Caligula. When Leo arrived in California, he immediately asked where Jason was, and his face crumbled when he realized what happened to his friend. Leo was teary eyed and looked like he had been struck repeatedly as a Piper hugged him, sobbing, telling him what happened to Jason. He looked at Jason's diorama after brushing the tears from his face, and said he never got to say goodbye. He sadly said that Jason did what he always did, saving the day. He then told Apollo to take Jason home and do right by him.
|-|Piper McLean=
Piper and Leo had known each other for a long time, for about a few months before the events of The Lost Hero. The two had trusted each other enough for Piper to tell Leo that her father, Tristan McLean, was a famous movie star, and Leo understood that Piper wanted to fight her own battles. Piper also knew that Leo ran away six times. However, when Leo got fake Mist memories of Piper and Jason, Leo felt like a third wheel to Piper and Jason when they were a couple. He was happy for them, but it made him feel like they didn't need them anymore. However, they were still friendly and Leo teased Piper about her stealing a BMW. Leo also winked and shot her a finger fun at the campfire. As for Piper, she thought a Leo was annoying, like when they were on the way to Camp Half-Blood, and thought he was hyperactive and made stupid jokes. Piper also thought that Leo was very ADHD. Unlike the other kids at Camp, Leo didn't make a big deal when Piper was blessed by Aphrodite, and thought it was amazing but didn't really care. Leo ended up repairing Festus so he, Piper, and Jason could go on the quest. Piper was shocked when she saw Leo with Festus, but said it was beautiful and was impressed by the machinery.
On the quest, Piper and Leo bonded. Piper saved Leo's life numerous times, like from Medea. Leo trusted Piper enough to tell her about Tía Callida, who was actually Hera, which he never told anyone before. He was also grateful when Piper and Jason weren't going to leave him alone with Calais, and willing to fight for him. Leo also reassured Piper that it wasn't her fault when Festus fell. However, Leo was slightly jealous of the two. He was excited when the mist memories were fake because he felt like it was a chance to reset their dynamic. But since Piper and Jason were heading to be a couple again, he thought they didn't want Leo around and he was worried being an odd man out again. He also felt like a reject when Piper and Jason got to see Boreas when he didn't. He was also worried she would think he was a freak when she found out he had fire powers. He ended up saving their lives from Ma Gasket and the Cyclops. Piper was very grateful when he saved her life and asked if he was okay, and Leo apologized for not telling her about the fire. But Piper grinned and punched his arm, saying it was amazing. Piper comforted Jason when Festus died. Leo also comforted Piper when he learned about her dad, and assured her that he will help her. Leo comforted Piper again when her father went home, giving her Kleenex, and Piper thought how much he meant to her. 
Leo and Piper later had a heartfelt conversation, with Leo comforting Piper about her dad. He reassured her that he will be fine with Coach Hedge protecting him. Leo was secretly struck by how much Piper had changed and seemed more present in the moment. He thought about how she spent her entire semester at the wilderness School trying not to be seen, and now she was impossible to miss. Piper confided in Leo about how she was worried about Jason, and that he may be the enemy. Leo was worried too, but reassured her that he wouldn't betray them after all they had been through, and said they were a team. Leo also realized that Piper was scared of losing Jason after losing her father, and couldn't imagine how it was for her to see her dad break down. Leo reassured her that she was the strongest, most powerful beauty queen he ever met, and she could trust herself and him. Piper was impressed later when Leo showed her and Jason Bunker 9.
In The Demigod Files, Piper and Leo were best friends. Piper helped Leo when he was stressed and when the Argo II almost exploded due to a malfunction, though she was confused at first. Leo thought that Piper's Charmspeak helped clear his mind and made his muscles relax, which he appreciated. Leo was not oblivious to her family stress and knew she was sensitive about both her godly and Cherokee sides of her family, though it was hard to keep track which made her more sensitive each day. The two and Jason cooperated well in defeating the Maenads and saving Camp. That night, Leo, Piper, and Jason drank hot chocolate at the campfire and Leo thanked Piper for saving him yet again. He enjoyed their company and they did a toast to friendship.
In The Mark of Athena, Piper wasn't angry at Leo when he fired on Camp Jupiter, and agreed that it couldn’t have been him, and could recognize the cold feeling he felt. Piper also figured out that Leo was possessed by Eidolons. Leo thanked Piper for not hating him after firing on the Romans, and Piper said it was okay, and he wasn't in control of himself. Leo said she didn't have to stand up for him, and Piper said of course she would, he was the annoying little brother she never had, showing how much she cared for him. Leo also teased Piper and said she had power ranger pajamas, and Piper said they were Cherokee Eagles. When Leo went missing in the Atlantic Ocean, Piper didn't sleep that night and looked in visions in Katoptris to find him. When Leo returned, Piper cried and freaked out, jumping in the ocean to greet him. She gave him a sisterly kiss on the cheek, with surprised him, and asked where he was. Piper wasn't afraid to lecture Leo, lecturing him when he didn't want to save Nico di Angelo and made Hazel upset. Leo saved Piper in Rome later on the quest, along with Percy, Jason, and Nico.
In The House of Hades, Leo wished Piper was with him at breakfast, since she had a way of calming people down, but she wasn't, she was with Gleeson Hedge. Piper and Leo also both wondered why Jason was suddenly defending Nico, since he didn't before. Piper recognized how Leo had changed over the months, and thought that he now knew how to use his nervous energy he had bottled up. Piper was heartbroken when Leo was shot up into the sky by Khione and demanded to know where he was. The idea of her never seeing Leo again made it hard to breathe and almost destroyed her. Piper was overjoyed when she reunited with Leo in Malta and tacked him with a hug. Piper was also concerned as to where Leo was and questioned him, but Leo brushed her off and said he didn't need an extra mom. 
In The Blood of Olympus, Leo and Piper were close and Piper knew whenever Leo was lying. Piper trusted Leo and told him how worried she was about Jason, which she didn't tell anyone else. Leo also recognized how Piper had changed in the last few months, and her Charmspeak was so powerful it made Leo nervous. He thought that if she asked Leo to eat his vegetables, he may actually do it. Leo was also the first person to compliment Leo on Piper's singing when she sang to Kekrops. Piper gave Leo a sisterly kiss on the cheek when he fished out the key for Asclepius's palace, He later went into Asclepius' palace in Epidaurus with Piper and Jason, and they defeated an Automaton of Hygeia. However, Leo kept his suicidal plan to save everyone a secret from Piper, and had Hazel give her a mist version of the cure and refused to tell her what Asclepius told him. Leo and Piper defeated Gaea, along with Jason, and Leo's last words were that he loved Jason and Piper. Jason and Piper looked for him, but couldn't find him. She was originally mad at Hazel and Frank when they kept his plan from her, but she agreed that it was a plan Leo would've done. Piper said that if he was here, she would kill him, and wondered how Leo took the cure alone. Piper and Jason then spent a night talking about Leo, and Piper hoped that Leo was alive, and out there. She felt guilty about his death and replayed the scene in her head, and felt like she failed him.
A month after, Piper got a parchment scroll that revealed Leo's location. She and Jason spent a month looking for him, until Chiron convinced them to stop so they could go to school. In The Hidden Oracle, and The Dark Prophecy, Leo expressed interest of seeing Piper again. Piper was very excited when she found out Leo was alive and shook Apollo after he told her. Piper and Leo finally reunited after Jason died and Piper hugged Leo and sobbed into his shirt, mourning for Jason. Piper expressed interest in Leo's life and whereabouts, and Leo told Piper that Hazel, Frank, and Reyna were okay. Both Leo and Piper were proud of each other and where they ended up, and Leo decided to escort Piper to Oklahoma with Gleeson Hedge, Chuck Hedge, and Mellie.
|-|Percy Jackson=
Percy and Leo first meet in The Mark of Athena, but Percy saw images and visions of Leo during The Son of Neptune. They're not particularly close and haven't gotten to know each other well yet, as Percy was initially angry at him for shooting on Camp Jupiter. When Percy was mad at him, Leo was scared, as he recognized the look that reminded him of the times Jason summoned lightning. However, Percy later agreed that it wasn't him who did it, and it couldn't possibly have been him. Percy was also initially cautious around Leo, and when he went with Hazel Levesque to Utah, Percy had a talk with Leo and told her Hazel's story, but gave him a look that said "If you mess with my friend, I will personally feed you to a great white shark." But throughout their journey, Percy befriended Leo and felt a responsibility for everyone on the Argo II, including Leo. Leo also heard about Calypso from Percy, who told him that she was nice and awesome. And while Percy was in Rome, when he saw the Colliseum, it reminded him of Leo. Leo ended up saving Percy, Piper, and Jason from Otis and Ephialtes, but wasn't grateful, and was angry that he hadn't rescued Annabeth first. After Percy fell to Tartarus, Leo was wracked with guilt and felt like the fortune cookie that Nemesis gave him that saved Hazel and Frank had cost Percy and Annabeth. However, Leo was determined to save his friend. 
In The House of Hades, Leo felt guilty about Percy and Annabeth and knew it was his fault, but knew that moping around wouldn't save him. However, after meeting Calypso, Leo felt a surge of anger towards Percy, and was mad at him for hurting Calypso. To make things worse, since Calypso clearly still had feelings for Percy, which made things ten times worse for Leo. Ultimately, however, Leo is the one to save Percy and Annabeth by flinging a screwdriver at the Doors of Death, managing to save them just in time. Leo was very happy when Percy survived Tartarus and whooped in happiness. 
In The Blood of Olympus, he loved all his friends, including Percy, and would do anything for them. However, Leo had mixed feelings about Percy. He didn't know what his deal was with blue food. Leo felt awkward hanging out with Percy and didn't know how to make conversation with a survivor of Tartarus. Percy intimidated him before, but now he was even more intimidating after being in the pit. He had trouble thinking of him as from the same Camp, since they never were at Camp Half-Blood at the same time, and that Percy had four beads, and Leo had none. The only thing they had in common was Calypso, and that made him want to punch Percy in the face. Leo wanted to bring up the topic to Percy, but the timing never seemed right.
They finally got to hang out when they went to Olympia together to find and capture Nike, along with Hazel and Frank. Leo and Percy searched the museum together to try to find Nike. The two skipped stones, and when Percy caught the rock Leo skipped, Leo wanted to show off by blowing up a tour bus with fire. Percy became uncomfortable when Leo angrily stared at him, and after Leo apologized, Percy suggested that they should talk, and Leo agreed. But they began to bond when Percy made a joke about saying Adidas was the best to Nike, and Leo realized that they had another thing in common: their same stupid sense of humor. Leo and Percy also teamed up to defeat Nike. While fighting her, they finally discussed Calypso. Percy said if they didn't make it out, he wanted him to know that he felt bad about Calypso, and felt like he failed her. Percy said even though he lost his memory and went on the quest, he should have made sure the gods freed her. He said he was glad Leo found her and promised that he would do anything to help Leo after they make it out. Leo then asked what his problem was, and said he was just as bad as Jason: he couldn't resent him for being all hero-y. He wondered how he could hate him after he apologized and promised to help. Percy smiled and apologized. Leo finally had no resentment towards Percy, and his anger began to unravel, now that he knew he had no feelings towards Calypso. He just couldn't dislike him after he apologized and acted all nice and sincere. 
After that, Percy and Leo were friends with no problems and they defeated Nike with the help of Frank and Hazel. Leo became sarcastic and joking with Percy, calling him "Water Boy", which he told him not to call him, then calling him "Aquaman", which he hated more. Leo was also miffed and asked him why he had to destroy the plumbing when he did. Percy also joked that if a statue engulfed people in fire, he should send Leo, and Leo jokingly said he loved him too. Leo was also grateful when Percy got everyone in the crew, including him, gelato, and said that it made his whole day better. Leo also joked about how Percy's zodiac sign was Leo's name. However, Leo kept his suicidal plan to sacrifice himself from Percy. Percy was devastated when Leo died, and was initially angry at Hazel and Frank, but his anger subsided when they cried and agreed that it was a plan Leo would've done. Percy was hopeful that Leo was alive and said that if he lives, they can take turns strangling him. 
In The Hidden Oracle, Percy realized that Leo was part of the prophecy to help Apollo and grinned when he saw him and Festus in the air. When Percy saw Leo, he was the only one not to punch him and gave him a hug, though he was disgruntled and couldn't believe he was gone for six months, and Leo explained he tried every way to contact him. After Leo said that he was in the Sea of Monsters, they bonded over how they hate the place and how they hate Polyphemus. Percy was surprised when Calypso called Leo, "Babe", though he supported their relationship wholeheartedly. When Leo said that it'd be easy searching the entire middle of the US for the second emperor, Percy noted that Leo was still sarcastic and Leo smiled, and said he had sailed with the most sarcastic scallywags on the high seas. They then gave each other a high five. After dinner, Percy said goodbye to Leo and the two embraced.
|-|Annabeth Chase=
Leo and Annabeth first met in The Lost Hero, when she rescued Leo, Jason, and Piper from the Wilderness School, and knew about their protector, Gleeson Hedge. Leo wondered what her problem was and why she was so angry until he found out that her boyfriend, Percy Jackson, was missing. Annabeth tried to get Leo to get along with Butch Walker on the way back to Camp Half-Blood, saying that he is the best equestrian and great with the Pegasi. Annabeth was also the one to tell Leo that he had been claimed by Hephaestus, the god of blacksmiths and fire, when he thought his head was on fire. Annabeth was also fine with Leo accompanying Jason on his quest to save Hera. 
By The Mark of Athena, Annabeth and Leo had become good friends and had helped build the Argo II. Annabeth thought Leo was seriously ADHD, even for demigod standards, and respected him as a mechanic. She thought he had an impish grin. As for Leo, he respected Annabeth as the leader and obeyed her orders, like when she told him not to put a smiley face on a scroll to the Romans at Camp Jupiter. Annabeth scared Leo and in return, Leo was scared to make her angry. He didn't find Annabeth attractive and ever since she had rescued him from the Grand Canyon, she changed his mind about blondes and now thought of them as much too smart and much too dangerous. Annabeth was shocked when Leo fired on Camp Jupiter, and thought that Leo would never do that and told Reyna that. In return, Leo was sad when he thought that Annabeth wouldn't trust him. However, Annabeth knew it couldn't have been Leo and agreed that it was most likely magic from Gaea or Octavian. Leo and Annabeth were the only people who could operate the engine room, so the two went in there a lot, with Annabeth going to help Leo in the engine room after he returned from seeing Narcissus, and the two staying behind in Kansas to make repairs after Leo needed Annabeth's help. Leo also joked around with Annabeth, and could not stop grinning when she spent the night in the stables with Percy. The two thought about each other, with Annabeth being worried when Leo went missing in the Atlantic and with Leo thinking about Annabeth when he saw the Pantheon in Rome. Annabeth also reassured Frank Zhang that Leo was a good guy and that he could trust him.
After Annabeth fell into Tartarus, Leo felt very guilty and was convinced that the code in his fortune cookie from Nemesis used to save Frank and Hazel sacrificed Percy and Annabeth, and blamed himself for them falling into Tartarus. Hazel reassured him that it wasn't his fault and Nico told him that Annabeth and Percy were not dead, and that they would make it through Tartarus. But he also was very determined to save them and head to Epirus. In The House of Hades, he still felt very guilty about her and tried not to think about her, feeling like it was his fault that she fell into Tartarus. He thought he should've realized the cavern floor was unstable and gotten everyone aboard safely, before thinking about the statue. But he knew that moping around wouldn't get Annabeth back. Leo ended up being the one to save Annabeth and Percy from Tartarus, by throwing a screwdriver and opening the mortal side of the Doors of Death. He was very happy and whooped when they came back safely.
In The Blood of Olympus, Leo respected and cared about Annabeth as a good friend, and she approved of Leo going to face Nike. While he was with Nike, he missed having Annabeth with him because she was good at talking. He also thought that Annabeth was no slouch. As for Annabeth, she liked Leo but would be a little strict with him as a leader, 
like when she also scolded Leo when he interrupted Piper while she was talking about her visions in Katoptris, and told him to be quiet, and when she almost objected with Leo meeting with Apollo and Artemis in Delos. Leo also called Annabeth "the architect", when they got to Epidaurus, and said she knew her stuff when she spotted where Asclepius lived. Annabeth also wished Leo good luck when he went to meet him. When the Argo II got to Athens, Leo, Frank, and Hazel talked strategy with Annabeth and planned a charge. 
Leo ultimately ended up sacrificing himself for everyone on the crew, including Annabeth, to make sure no one else would die, and kept his secret from Annabeth. Annabeth was devastated when Leo died and was furious at Hazel and Frank for keeping it from her, but her rage dissipated when they cried and she agreed that it was exactly a plan Leo would've done. It is unknown if they met again, because when Leo visited Camp, Annabeth was in Boston visiting Magnus Chase. 
Interestingly, both of them can communicate in Morse Code.
|-|Nico di Angelo=
In The Mark of Athena, Leo was suspicious of Nico’s loyalties, due to knowing about both camps, and thought rescuing him was a trap. However, after Hazel fought with him and Jason, Leo decided to rescue him for Hazels sake and apologized to her, even though he thought he was suspicious for a good reason, and knew he had to travel fast to rescue him before it was too late. Leo even helped pinpoint Nico’s location with Hazel and Frank, and rescued him, Percy, Jason, and Piper On Nico's end, he was very grateful that Leo rescued him and thanked everyone, including Leo, for rescuing him. After Percy and Annabeth fell into Tartarus, Nico reassured him that they were alive and that if they were dead, he would feel it. However, Leo was still creeped out by Nico and did not like how he hesitated if Percy would survive.
In The House of Hades, Leo was very creeped out by Nico and said he gave him the freaky deakies, thinking his eyes were sad and empty as if he stared into Tartarus, which he did. Leo would often make jokes at Nico's expense, which Jason would often chastise him for. Leo once commented to Jason and Piper that Clytius reminded him of Nico and wondered if they were related. Nico, on his end, was frequently annoyed by Leo’s humor. While they were fighting the Ourae, Nico got annoyed when he said that masts didn't come from trees, and he frowned and said that they are from trees, and Leo retorted that it wasn't the point. And on the way to the House of Hades, when Leo kept joking, Nico told him he wouldn’t keep his sense of humor for long. Nico also became more defensive around Leo after Croatia, due to being worried about what he would say while he was gone. However, Leo and Nico collaborated well on defeating the Ourae and both worried about Hazel while she was gone with Hecate. Later, when Nico fell a few days later, Leo hoped he was okay, and he wholeheartedly supported his plan to get Diocletian's Scepter, saying he wanted Pagan Zombies to fight with. After Leo came back from Ogygia, Nico was glad to see him and shook his hand.
In The Blood of Olympus, it is revealed that Nico greatly cared about Leo, since him and the rest of the Seven didn't overlook him like the others and welcomed him onto the ship, and learning that he (and any other of the seven) may die made him feel like he was back in the glass jar again. Later, when he arrived at Camp Half-Blood, and the Argo II exploded, he was worried about Leo's fate and reassured Jason that he would be fine, but just in case, they charged into battle "for Leo". Nico eventually let the onager hit Festus and kill Leo, knowing that some deaths couldn't be prevented, listening to his father, but almost lost his nerve knowing he let his friend be killed.
After his death, he honored Leo and the dead and oversaw the burial rites, and knew that Leo had made a real sacrifice. Nico thought that talking to the other demigods about Leo's death was the hardest part of him dying. Out of all the demigods, Nico the only one not mad at Hazel and Frank for what they did, because he knew what Leo did was a sneaky, twisted, ridiculously annoying and noble plan he would do. Nico knew better that Leo was dead, telling Jason so, and said that he felt his death. However, Nico was wracked with guilt of his death and replayed the scene of his death in his mind for two days after it happened, and wondered if what he did unnecessarily cost him his life. His death even led him to pray to his father for guidance for the first time. Even though Nico felt guilty himself of what happened, he reassured Jason and Hazel that it wasn't their fault. Nico also sensed that there seemed to be something different about Leo's death, possibly sensing that Leo had in fact been resurrected but not understanding it.
In The Hidden Oracle, it is revealed that in September, after the events of his death, he and everyone else received a parchment scroll from Leo saying what happened. Nico was very angry at Leo for not contacting camp after and would hold the scroll and watch it every time he wanted to be angry at him. In Camp Half-Blood Confidential, he was miffed at Leo she remarked that he was supposed to stay dead. Nico remarked to Apollo when they sat at dinner together that if he sees Leo again, he'll kill him. However, when Leo returned, Nico arranged a single file line at Camp to punch him and even made a ticket dispenser, taking numbers, leaving Leo to ask if that was really necessary, which the other campers agreed. After the punching was done, Leo yelled for Nico and asked if he was done with the physical abuse, and Nico smiled, saying there are plenty of people on the West Coast who want to punch him. 
|-|Hazel Levesque=
Hazel Levesque and Leo first meet in The Mark of Athena, but first sees him in a video scroll during The Son of Neptune. When they meet at Camp Jupiter, Hazel is very suspicious of Leo and kept frowning and looking at him. They first had a proper conversation in Salt Lake City, and he found himself to be infatuated with Hazel. Hazel studied Leo, which made Leo feel self conscious, but also wondered if they met before. Hazel and Leo ended up going on Arion to Salt Lake City together after Hazel insisted. Leo liked Hazel even more after he found out about her story from Percy, and thought she seemed warm and alive, and good with people. He knew he should keep his distance from her since she was dating Frank, but thought her hair smelled good and riding with her with his hand around her waist made his heart race. Eventually, Hazel brought up the subject of Sammy with Leo, saying he looked so much like him, which embarrassed them both. While travelling through the city, they had plenty of awkward moments, like when Hazel caught Leo's hand when he almost fell, making the two be face to face. But the two became friends after they defeated Narcissus.
After their quest in Salt Lake City, their relationship was a little strained as they had complicated feelings for each other. Hazel and Leo knew they had a history, and it was made worse when Frank got jealous and would argue with Leo. Hazel hated when they argued and would try to stop it. The two became slightly more tense when Leo was against rescuing Nico di Angelo, though he eventually apologized to her at Jason's insistence. Leo even later offered to use the fortune cookie to find Nico to make it up to her. Hazel and Leo were alone again while in the Atlantic Ocean, and the two finally talked about Frank's tension with Leo and what happened at Salt Lake City. Hazel decided to show Leo about who Sammy was by pulling him into a blackout, so they could finally understand how they were connected. Leo agreed to it and the two learned that Sammy was Leo's great-grandfather.
Frank became furious at Hazel and Leo when they found out they were holding hands and staring into each other's eyes, because he didn't know it was a blackout. Leo later reassured Frank that he did not like Hazel in that way, but even he was unsure how he felt about her. He thought she was awesome and cute, and he had a weakness for girls like her, but seeing the flashback complicated his feelings for her a lot. Leo was determined to save Hazel after they got lost in the Atlantic Ocean, worried that she was in trouble. Hazel was overjoyed to see Leo once they reunited at Camp Fish-Blood, beaming at Leo. Leo was very impressed with Hazel after finding out she befriended everyone at Camp Fish-Blood, and thought she seemed beautiful and sure of herself, the opposite of her old self from the 1940s. After Leo brought up Sammy against Hazel told Leo that she needed time for the whole Leo/Sammy thing to sink in and process it.
Once they got to Rome, Hazel wanted Leo to go on the quest with her and Frank to find Nico, which made Frank's smile look like Chrysaor's mask. The two were very tense, and Hazel was annoyed at Leo for not being impressed with the scenery in the city. Leo also felt awkward that Hazel mostly talked to Frank and not him, as if Leo ceased to exist. Hazel was also mad at Leo when he implied that Frank was fat, and when he kept arguing with him. Leo was also worried about Hazel after she left for awhile, and he and Frank both agreed to find her. But after Leo saved Frank and Hazel from Eidolons and made a plan to get to Nico, Percy, Jason, and Piper, the tension between Hazel and Leo subsided. After Percy and Annabeth fell into Tartarus, Hazel was the only one who understood why Leo blamed himself, since they both met Nemesis in Salt Lake City. Hazel insisted that it was Gaea's fault, not his, and gripped his hand, telling him that after what happened to Sammy, she cannot bear him to blame himself for another thing that happened.
In The House of Hades, the two had become good friends, though there was still a level of tension between the two. Hazel was very worried about Leo after Percy and Annabeth fell into Tartarus, since he was being more hard on himself than usual, but also thought he sometimes reminded her too much of Sammy when he smiled and joked. As for Leo, he was very infatuated by Hazel and sometimes thought she was hot, which he felt very guilty about. Nevertheless, the two deeply cared about each other and helped thwart off the Ourae on the way to Epirus. Leo was also very worried about Hazel after she met Hecate and caught her after she fell. Hazel also wished that Leo was with her instead of Jason when she went to defeat Sciron. Hazel was extremely relieved when Leo came back from Ogygia, and felt comfortable enough with him to give him a sisterly kiss on the cheek. But she soon was extremely worried after he avoided the subject, and Leo brushed it off, saying he didn't need an extra mom. After they got back on the ship, Hazel realized he met someone after Leo didn't give longing looks to her and seemed less tense with her. 
After the two got separated from the others in the House of Hades, Hazel finally decided to bring up Sammy again to Leo. Hazel apologized for leading him on, thinking he was Sammy, and making everything awkward between the two, even if she didn't mean to. Leo reassured Hazel that it was okay, and that they met for a reason. He reassured her that she and Frank were good together and that he was happy for them, and hoped they had a chance to ne happy once everything was over. Hazel was grateful for what Leo said, and called him a philosopher. Hazel was relieved and finally felt like something was untangling inside her, finally finding a good friend. Hazel asked Leo what happened while he was gone and if he met someone, and Leo promised to tell her later, once they got out of this. The two collaborated well on defeating Pasiphaë and Clytius, and even held hands without it being awkward. 
In The Blood of Olympus, Hazel finally got Leo to spill about Calypso, and drew a portrait of her that looked just like her. Leo loved all of his friends, including Hazel, and would do anything for them. Leo thought that Hazel was a good listener and sat next to him at breakfast because she was the least likely to punch him after he made bad jokes. Hazel and Leo went with Percy and Frank to go subdue Nike/Victoria, and even though he wasn't infatuated with her anymore, he was super impressed with her for everything she did in the House of Hades, and looked at her in admiration while she was riding Arion. Hazel could tell what he was thinking, and blushed, flustered. Hazel later rolled her eyes at Leo and Percy when they made dumb jokes, calling them both impossible. Leo was very worried when Hazel got injured while fighting and wanted to rush into the field to save her. Leo called Hazel awesome and did an impression of her after the fight was over.
Once the Argo II made it to Delos, Leo wanted Hazel and Frank to come with him because he trusted the two more than the others to know about his suicidal plan to sacrifice himself. Hazel was very upset when she heard the news, and a tear fell down her cheek. Leo told Hazel that she was the only one who could cover for him, since Sammy knew how special she was. He said that he blessed him when he was a baby because he knew that Hazel would help him, and that everything was leading up to it. Hazel burst into tears and hugged Leo. Hazel said that she hated the plan, but she would do it for him. Hazel ended up making. Fake mist version of the Physician's Cure and gave it to Piper.
After Leo died, Hazel tearfully revealed her plan to the others, after telling Piper that the cure was fake. The others were initially angry at Hazel for helping Leo, but after Hazel cried they knew it was exactly what Leo would've done. Hazel could feel Leo's death and knew better than the others to think he was alive, which made her feel even more guilty about the situation. On her second night at Camp Half-Blood, she broke down in front of Nico, saying that she shouldn't have helped him take the cure and that he could not have possibly survived the explosion. She wished he hadn't died alone, and broke down after she realized there was no one to give him the cure, no one to find the body, and no one to help him. She cried until she fell asleep from exhaustion.
In September, Hazel got a parchment scroll from Leo confirming he was alive. In The Hidden Oracle and The Dark Prophecy, Leo expressed interest in seeing Hazel again and went to Camp Jupiter to help her and the others defeat Caligula and warn them about his assault on the camp. Everyone, including Hazel, went into a line and punched him. Leo was relieved that Hazel was okay. 
|-|Frank Zhang=
Frank and Leo met in The Mark of Athena and had a rocky start. While Frank watched Leo once they got back on the Argo II, Frank was skeptical of him and asked if his name was Sammy, which confused Leo. However, Leo was grateful for Frank for not hating him, despite him firing on Camp Jupiter after he suggested Octavian may have done it. Leo also introduced Frank to Festus. At first, Frank didn't trust Leo and scowled when he said he wanted to go with Hazel to retrieve lime for ship repairs, which only motivated Leo even more to prove that he was trustworthy. Throughout the earlier stages of their acquaintance, Leo and Frank got into numerous small arguments. One of such is when Leo asked Frank why he didn't always turn into a dragon, since it was such a useful form to take the shape of. Frank replied, saying it was because shapeshifting is hard, like lifting weights. Leo said he wouldn't know, since he didn't lift weights, to which Frank began to respond, telling him he should consider trying it out. Shortly after, Hazel stepped in to cut off the argument. Frank also got angry at Leo when he didn't want to rescue Nico, taking it as a sign that Leo was skeptical of both Hazel and Nico's loyalty. In Atlanta, Leo embarrassed Frank when he teased him for not figuring out Chinese handcuffs, and he said he was worth at least two or three Franks when he and other members of the Argo II were wondering how much each of them would be worth. Annabeth later reassured Frank that Leo was nervous around him, and he was a good guy. Hazel also told Leo that Frank was nervous around him due to his fireballs, since Frank's main weakness is fire, due to his fragile lifeline depending on a piece of firewood.
They got into a fight in the Atlantic when Frank was reluctant to leave Leo alone with Hazel. When Coach Hedge said that Leo and Hazel were holding hands, Frank freaked out and was furious at Leo. While Leo and Hazel were talking about her past together in a shared memory, Leo awakens to find out that the ship as been attacked. After he and Frank fall overboard, they wake up in a cave underwater. Frank wasn't happy that he was stuck with Leo, and told Leo he obviously cared more about this ship than his friends due to his carelessness. Leo realized that Frank was angry about him holding hands with Hazel, and apologized, saying they were in a blackout in order to find his connection with Sammy. Frank became curious, and Leo said that he was Sammy's great great grandson, telling Frank the whole story in the process. Leo also told Frank that he was not trying to date Hazel, even though his feelings were complicated. They both decided to make a plan to get out of the cave since Frank couldn't shapeshift, and Leo tried to free them with fire, making Frank freak out. Leo soon realized that Frank had a bad experience with fire in the past, just like him. In order to ensure Frank that he wasn't alone in his bad relationship with fire, he told him how his mom died. Frank almost told him about his lifeline until Bythos interrupted.
Frank and Leo's relationship was better after that, but still rocky. When Hazel wanted Leo to go with Frank and Hazel in Rome, Frank's smile looked like Chrysaor's mask. While in Rome, Leo insulted Frank by saying he needed to be skinnier to get through a hole in a wall. Leo and Frank also argued about what Frank should shapeshift into until Hazel told them to stop. When the two were alone, Frank said that Hazel said that Leo knew about his lifeline, and Leo reassured him that he wouldn't do anything to hurt him. Frank told Leo about his grandmother and the fire, and how his mom died, making Leo realize they both lost their moms to a fire. Leo told Frank the whole story about how his mom died, and Frank said even though he hates when people say "I'm sorry about your mom", he said that to Leo, and he accepted it. Leo reassured Frank that they all have weaknesses, with Leo being tragically funny and good looking, and they both agreed to look for Hazel. Leo ended up using his fortune cookie from Nemesis to save Frank and Hazel. When they returned to the Argo II, Leo thought it was cool that Frank knew Chinese, and said he was amazing.
In The House of Hades, Frank and Leo were friends, but still had a rocky relationship. Frank mentioned how his aunt and Leo's grandma would get along, and Leo felt bad that he missed Canada day, and asked Frank if he should have gotten him a present. As for Frank, he revealed that in his head, Ares and Mars told him to kill Leo, and Ares told him to retaliate to every insult he gave him, since he teased him a lot. Leo's comment that he made in Atlanta about Leo being worth two or three Frank's hit too close to home for him, and it hurt his feelings. Leo also has a tendency to annoy Frank a lot with his stupid jokes, and when Leo made a pun about the town of Split, Frank groaned and asked Jason to leave him in Croatia. The two sometimes agreed with each other, like when they both thought there were too many monsters in Croatia. Frank also wanted to be there for all of his friends, including Leo, since Annabeth was gone.
After Leo returned from Ogygia, Frank was happy to see him and patted him on the back so hard he winced. Frank realized that Leo had changed since Ogygia, and that he didn’t tease Frank much or steal glances at Hazel. Frank was amazed how Leo's tension with Hazel had disappeared. Frank was relieved that Leo wasn't hitting on her, but he was worried about him, even after their differences, and after all they'd been through, he didn't want his heart broken. Leo later asked Frank for his firewood, and though Frank was reluctant, he gave it to him, and trusted Leo. Leo ended up making a fireproof bag for Frank's firewood, and Leo wanted to light it to test it. Even though Frank was skeptical, he realized he trusted Leo after he saved him in Rome. The bag ended up being fireproof, and Frank was grateful to Leo and thanked him, even though it seemed inadequate after what he had done for him. Leo accepted it and said he was his best buddy. Later, Leo told Hazel he was happy for her and Frank, and hoped they would be happy. Leo also said Frank had moves and would be alright. Leo was happy that Frank was promoted to Praetor, and clapped him on the shoulder, saying he can order Octavian to fall on his sword.
By The Blood of Olympus, Leo and Frank were close friends. Leo was supportive of his relationship with Hazel and thought they were cute together, reminding him of an old married couple. Leo couldn't believe how much Frank had changed in the last few weeks, and thought he was more confident and more willing to take charge. He could barely see him as the the klutzy dude who couldn't get out of Chinese handcuffs just a few weeks ago. Leo and Frank went with Percy and Hazel to defeat Nike in Olympia, and he was grateful when he came back so he wouldn't have to talk to Percy. Frank was slightly offended when Leo didn't know who Pelops was, but more in a teasing way. 
Later, when they went to Delos, Frank went with Leo and Hazel, at Leo's insistence. After they met with Apollo and Artemis, they both told each other about what they heard. Leo then revealed to Hazel and Frank how he was planning to sacrifice himself to save everyone, and survive by taking the Physician's Cure. Frank was shocked, but Leo told them he told them because they are Romans, and they knew a lot about sacrifice. Frank choked up, and Leo said he was counting on him, and that since his father told him to step up, he would have to make the call other people aren't willing to make. Frank cried and hugged both Leo and Hazel, which Leo was weirded out by. Leo asked if he was in agreement, and Frank said he hated the plan, but he would do it. The next day, Frank gave Leo the Pylosian Mint and told him not to break it. Leo joked about how not breaking deadly poison would've never occurred to him, and Frank told him to shut up and gave him a hug, telling him to be careful. Frank kept Leo's plan from the others at his insistence. After Leo died, Frank was devastated and cried, tearfully telling the others. They were all mad at Frank until they couldn't be mad at him while he was crying, and they agreed that was a plan Leo would've done.
In The Hidden Oracle, Leo expressed interest of seeing Frank again. In The Dark Prophecy, after Leo found out that Camp Jupiter would be attacked, he flew on Festus to Camp Jupiter to warn him and the camp. Everyone, including Frank, got in a line and punched him, then Leo helped them prepare for the battle. In The Tyrant's Tomb, Frank was grateful that Leo came and told Apollo they would've lost the battle if not for him. Frank said he was mad at him for making him worry about him, but was happy to see him. As for Leo, he was glad Frank was okay.
|-|Reyna Ramírez-Arellano=
Reyna and Leo first meet in The Mark of Athena, where Reyna welcomes Leo to Camp Jupiter, along with Piper, Jason, and Annabeth. Jason introduced Reyna to Leo, and Leo grinned at her and gave her a peace sign. Though Reyna and Leo didn't have a one on one conversation, Leo ate lunch with Reyna and the others in the forum. Reyna also trusted Leo enough to have him show Octavian the Argo II. However, Reyna quickly grew to distrust Leo when he fired on Camp Jupiter, even though he was possessed by eidolons, and was angry that he betrayed her trust. Annabeth later tried to convince Reyna that Leo was innocent and that it was Gaea's fault, but Reyna didn't listen, and thought someone must pay for what happened. 
In The House of Hades, Leo knew about Reyna flying across the Mediterranean, and while on Ogygia, he saw a holographic image of Reyna flying across the sky, being attacked by Gryphons and venti. When the image in the mirror went black, Leo banged on the mirror and wanted to see what happened to her, and asked if Calypso could sing again. Calypso was suspicious and asked if she was his girlfriend, and Leo said that she wasn't and he needed to see more, proving even though he didn't know her well, he was very worried about her. When Reyna arrived, Leo, along with the rest of the crew, welcomed Reyna on to the ship, and Leo showed Reyna the Athena Parthenos, and when she commented it looked newly made, Leo said he just used some windex and dusted off cobwebs. During lunch, Leo questioned how Reyna could get the statue to Camp Half-Blood without Scipio, but quickly apologized. Reyna snapped that it was fine, due to not having a soft spot for Leo after him firing on Camp Jupiter, and not fully forgiving him. Reyna did agree with Leo, and asked how she could transport something so large. 
A month after the events of The Blood of Olympus, Camp Jupiter received a parchment scroll confirming his fate. In The Hidden Oracle, Leo expressed interest of seeing everyone at Camp Jupiter, including Reyna, and thought it would be fun. In The Dark Prophecy, Leo decided to deliver a message to Camp Jupiter to tell them about Caligula's attack on the camp. Leo said that he wanted to see Reyna again, even though she scared him. When he arrived at Camp Jupiter, everyone at Camp Jupiter made a line to punch him, including Reyna. Leo also helped Reyna and the others with the battle. In The Burning Maze, he was glad that Reyna was okay. 
In The Tower of Nero, Reyna and Leo had become good friends and had developed a sibling like relationship, with Reyna and the Hunters of Artemis visiting the Waystation. Reyna affectionately called Leo "mi hermano". During one of her visits, she heard Leo talking about his relationship with Calypso, and she said they needed a heart to heart. Reyna squeezed his shoulder and told him that he cannot call a young lady "mamacita". Leo was ready to protest, but he thought about it and said okay. Reyna then told Apollo that he grew up without his mom, and never learned those things, but now he has two foster moms and "his big sister" to smack him when he gets out of line. Reyna then flicked her finger on his cheek. Leo said that that’s the truth and Reyna told him to cheer up. She said that Calypso will come around, and that he can be a doofus, but he has a heart of Imperial Gold. The two also speak Spanish to each other. 
|-|Gleeson Hedge=
Leo and Coach Hedge knew each other for a few months before The Lost Hero, when he was Leo's protector at the Wilderness School. Leo had little respect for the Coach and liked to mess with him, like making his speaker say "The Cow Says Moo" on a field trip to the Grand Canyon. This made Coach very angry and ended up assigning the entire bus back row for lunch duty. Coach Hedge had a tendency to force Leo to do push ups. Leo also hated the educational field trips that the Coach would take them on. However, Coach Hedge secretly cared about Leo, who was one of the demigods he was assigned to protect, along with Piper. He even jumped off a cliff to save Leo from Dylan, getting captured by Medea in the process. 
Leo, Piper, and Jason eventually saved the Coach and unlocked him from his cage. Leo was very relieved when he was okay. Leo was the first one to comfort the Satyr and tell him that things were okay, even stepping in front of him as he swung his bat. Coach Hedge thought that he was destined to protect Leo and join the quest with them. Leo slowly became on good terms with the Coach over the course of the quest, telling him to give Jason and Thalia Grace some space when she wanted to talk to Jason. Leo even agreed that Coach Hedge was terrifying at fighting. Leo was still very annoyed by the Coach though, like when he told him to pick up the pace on the way to Aeolus's palace and began to sing. When the Coach said goodbye to Leo, he told him to protect Piper. Leo smiled at him and promised he would.
By The Mark of Athena, the two were on friendly terms, though he thought it was weird that he carried around his baseball bat everywhere. He even would obey Leo's orders sometimes, like when he told him to stay above deck. Coach Hedge was impressed after Leo (possessed by Eidolons) attacked by Romans, but was angry that his attack interrupted his wrestling match, breaking the satellites. As for Leo, he wondered why people would think the Coach was a responsible chaperone. However, Coach Hedge revealed that he had a gentle side to Leo. After Leo steered the Argo II for two hours, he spoke to Leo with a surprising gentleness, telling him to give him the wheel to steer it. He managed to pry Leo off the wheel after Leo couldn't himself. Leo tried to order the Coach around, but he told him to go away and that he could handle it. 
In The House of Hades, Coach Hedge was overjoyed to see Leo alive after he was blasted off the ship by Khione, yelling his name and grinning at him, but he quickly regained his composure, remembering he was supposed to act tough. He scowled, and told Leo that if he disappeared again, he would knock him out, calling him a little punk. He was still protective of him, and offered to fight Calypso for him if she was hurting him.
In The Blood of Olympus, Leo decided to program Buford to say things that Coach Hedge would say, after recording the Satyr's voice. He laminated the table with a magic scroll, making a holographic image of Coach Hedge pop out. Leo even admitted that he missed the Coach while on his shadow travel expedition.
|-|Will Solace=
Will was the one to first explain to Leo in The Lost Hero what it means to be a demigod, tell him about Percy Jackson and the Titan War, while taking him on a tour of Camp Half-Blood and the Hephaestus's Cabin. Leo considers Will "pretty cool" and the tour itself "amazing". Will is also among the first to punch and greet Leo in The Hidden Oracle.
|-|Apollo=
Leo meets Apollo on the island of Delos, and asks him where to find the Physicians Cure in exchange for the Valdezinator, which Apollo excepts. Apollo has a great deal of respect for Leo, remembering his name because if the Valdezinator. In The Hidden Oracle, Leo agrees to help Apollo, and walks him to the bonfire for s'mores. 
In The Dark Prophecy, Leo, Calypso, and Apollo go west to Indianapolis to find the Cave of Trophonius, and the three travel for six weeks and become close friends. Leo is one of the first people to find out about what he did to Commodus, and he understands. Leo also tells Apollo that he sometimes thinks Calypso blames him for not having powers.
When Leo says he is staying at the Waystation with Calypso, Apollo is supportive of his decision, even though he will miss him.
|-|Lityerses=
The two first meet at Midas' palace in Omaha, and they fight. They meet again in The Dark Prophecy, where he is on the side of Commodus. Lit reveals that he holds a grudge against Leo for his role in King Midas' second death and Lit being trapped in the form of a statue. In turn, Leo states that he hates Lit and only reluctantly has Festus rescue him from execution. However, Leo tells the dragon that if Lit acts out, to smash him against a skyscraper.
Lit decides to fight on the side of the heroes, and Lit and Leo befriend each other during the battle. Lit gains Leo's respect when he smashes Commodus through a window, and they fist bump. They are currently living in the Waystation together.
</tabber>
===Family===
<tabber>
Esperanza Valdez=
Leo is shown to love his mother very much. Esperanza is very protective and caring of him. The two had a very strong relationship and Leo was devastated when his mother died. He blames himself for her death, and for that reason, didn't use fire again until he needed to in order to help his cabin. When Leo defeats Gaea, he yells that it's for his mother.
|-|Hephaestus=
When Leo and Hephaestus first meet in The Lost Hero, it began with Leo telling him off for disappearing from his life. Hephaestus laughs at this, saying Leo reminds him of Esperanza, whom he misses quite a bit. Hephaestus later reveals that he has been watching Leo, and that he is very proud of him. He also admits that he is not very good with people, which is why he doesn't meet with his children often. When Festus is destroyed, Hephaestus takes his head to Bunker 9 upon Leo's request. In The Blood of Olympus, they meet again, and courageously fight the Giants side by side. Hephaestus compliments his son's work on the Argo II as well.
|-|Sammy Valdez= 
Leo has met his great-grandfather, but was not old enough to remember. The name 'Sammy' sounded familiar to him, but he couldn't place who it was. After looking at Hazel's past, the memories showed a moment where an old Sammy was talking to a baby Leo. Leo and Sammy have very similar personalities and appearances, which is shown when Hazel believes Leo to be Sammy. Leo however feels that he is only an imitation of Sammy after seeing Sammy's quick wit and how charming he was with the girls, unlike himself.
|-|Rosa Valdez=
Leo hates his Aunt Rosa. After Leo's mom died, she blamed Leo for the death, calling him a devil. She turned the entire family against him, leaving him with nowhere to go. Because of her refusal to take him in, Leo was sent to a foster home, and his life of running away began. When Leo meets Nemesis he sees her in the form of Aunt Rosa, meaning she is the person he wants revenge from most. 
|-|Nyssa Barrera=
Though not much is shown of Nyssa, Leo's first impression of her is that she is very serious. This is because of the Curse of Cabin 9. She is the one who explains the curse to him, and she congratulates him when he returns from his quest. She also helped him work on the Argo II, along with the rest of the Hephaestus' Cabin.
When Leo returns in The Hidden Oracle, Nyssa slaps him and yells at him angrily in Spanish. 
|-|Harley=
Harley missed Leo while he was missing very much, and made a beacon for him so he could find home. Apollo tweaked it, and Harley succeeded. When Harley saw Leo, Harley was first mad at him, but then hugged him and cried. Leo mentions in The Dark Prophecy that if something ever happened to Harley, he'd be extremely angry.
|-|Jake Mason=
When Leo meets Jake, Jake gives him Charles Beckendorf's old bed. He later steps down as head counselor of Cabin 9 in favor of Leo. 
|-|Charles Beckendorf=
Leo never met Charles, but has a lot of respect for the counselor and is aware of his sacrifices. Leo slept in Charles's old bed during his stay at Cabin 9. 
|-|Josephine=
Emmie shows Leo to Jo in The Dark Prophecy. Leo bonds with Josephine immediately for their shared love of mechanics and technology. Leo immediately goes to hang out with Jo. The two later help Calypso go to the infirmary. They later help rebuild Festus.
In The Tower of Nero, Jo tells Apollo that Leo has a lot of potential and Leo calls her Mom. Reyna suggests that Emmie and Jo have become Leo's surrogate mothers, stating that Leo now has two foster mothers and a big sister to teach him the things that Leo's own mother never got the chance to teach him.
</tabber>
== Etymology ==
* Leonidas is derived from the name Leon, similar in meaning to his nickname Leo. The suffix, "-idas", was likely intended to make this a Greek patronymic name. If so, Leonidas means "son of Leon".
* Leo is a given name of Latin origin meaning "lion".
* Valdez is a Spanish surname derived from Valdés, a municipality in Spain's Asturias province in the northern part of the country.
==Trivia==
*He is currently the only known living son of Hephaestus who has been given the gift of Pyrokinesis. The previous one is Thomas Faynor known for having caused the Great Fire of London in 1666.
*Because of his pointy ears and his friend Jason Grace calling his dad Vulcan instead of Hephaestus, Leo claims that he doesn't even like Star Trek, a reference to Spock, one of the main characters of Star Trek who is a Vulcan.
*Leo's favorite color is red, as revealed during his time on Ogygia.
*When Jason learns that Leo is a fire-user, he theorizes that Leo could fly just like he can by yelling "Flame on!", a reference to Human Torch of the Fantastic Four in Marvel Comics.
*He is the only one of the seven to not have lived in California at any point in life.
*The name Leo is one of the three zodiac signs which has fire as its element.
*In Latin, Leo means "Lion".
*In Teutonic, Leo means "Bold to his people".
*Leo, Jem Asturias, Nico di Angelo, Frank Zhang, Nyssa Barrera, Reyna Avila Ramírez-Arellano, Hylla Ramírez-Arellano, Chiara Benvenuti, Paolo Montes, and Hazel Levesque, are the only known demigods that can speak two or more languages (that has nothing to do with them being a half-blood), as he, Nyssa, Reyna, Jem, and Hylla can speak Spanish, Nico and Chiara can speak Italian, Paolo can speak Brazilian Portuguese, Hazel can speak Louisiana French, and Frank can speak Canadian French, along with "a little" Chinese.
*Leo looks almost exactly like Sammy Valdez, Hazel's old boyfriend from the 1940s.
**This is because Sammy is his great-grandfather, as stated in The Mark of Athena. Sammy jokes that Leo could be his stunt double.
*While Leo is a son of Hephaestus, he shares many traits with the children of Hermes, including elvish ears, a mischievous smile, and a love for practical jokes.
*It is said by Annabeth that even by demigod standards, Leo is seriously ADHD.
*Leo Valdez and the Quest for Buford is in his point of view.
*Leo once reprogrammed all the electronic billboards in Times Square to read "ALL DA LADIES LUV LEO!" (accidentally, of course)
*It is stated in The Mark of Athena that Leo gets carsick.
*Leo has a cousin named Raphael and an aunt named Rosa, both of whom Leo doesn't like very much.
*In The Mark of Athena, Leo says "One basketball to rule them all". This is a pun on Lord Of The Rings, "One ring to rule them all".
**The Lord Of The Rings was Rick Riordan's favorite book series when he was younger. 
*Leo's least favorite line in the prophecy is "To storm or fire the world must fall".
*He and Hazel Levesque are the two people out of the Seven that have died and been resurrected.
**Although Jason might also qualify as resurrected, as Jason's soul was charmspoken to return to his body by Piper McLean in The Lost Hero, though that was due to Death being chained up at the time, as revealed in The Son of Neptune.
*Leo is the second known child of Hephaestus to die in an explosion. The first one was Charles Beckendorf.
*Leo is the only male demigod of the Prophecy of Seven who wasn't praetor of the Twelfth Legion.
*Leo is the only known demigod that had run away six times from foster homes.
*Leo is the only person to find Ogygia twice.
*Leo is the only character who appears in both the very first and the very last scenes of The Heroes of Olympus series.
*In The Blood of Olympus, it is inferred that Leo had an abusive foster mother, Teresa.
*It is surmised that Leo's full name is Leonidas, as Calypso once called him by it.
*Leo, along with Percy, Jem, Matt, Meg, Nico, and Will, are the only known demigods to be mostly called by their shortened first names. Even more than Leo's real first name is not revealed until the sequel series to the series he was introduced in.
*In The Lost Hero, Leo's motto is revealed to be "keep moving to escape the pain."
*Leo is also a constellation in the sky.
*In The Dark Prophecy and The Demigod Diaries, it is stated that he does not like being called short.
**In The Demigod Diaries, he bites back "some choice words" when he meets the maenads, who comment on his height.
*Out of the seven, Leo had the most lines in the prophecy that was about him, or partially about him.
*Leo and Annabeth are the only two of the seven who have run away from home, though Jason was taken from his mother and sister when he was younger.
*Leo is the first known demigod of Mexican descent, the second being Alex Fierro.
*The recurring idea of being the seventh wheel associated with Leo may have something to do with his eventual sacrifice, as seven means 'ghost' in Chinese as stated by Frank's grandmother.
*Leo is the only person to physically appear in all 5 books of The Heroes of Olympus as he was in a video in The Son of Neptune.
*As revealed in The Demigod Diaries, when Leo is stressed, he sometimes slips into Spanish.
**This is similar to Nico, as in The Tower of Nero, Will states that Nico slips into Italian when he's really upset.
**This is similar to Jem, as throughout the original series, Percy mentions that Jem slips into Spanish when stressed.
*He is the third character shown to wield fire in the books, preceded by Hephaestus and Hestia.
*In The Demigod Diaries, Leo sings the theme to the tv series Psych while trying to fool Dionysus' followers. Coincidentally, Timothy Omundson, one of the main cast members of the TV series, would later come to play his father Hephaestus in the live-action tv series adaptation.
Category:Greek Demigods