Cleo Sertori

Cleo Sertori is one of the three main protagonists in the television series H20: Just Add Water. She is a land girl who became a mermaid after bathing in the Moon Pool on Mako that gave her powers as a mermaid, which she transforms into whenever she gets wet. In the second season, Cleo gains the power to control and manipulate water and, later, wind and the weather.
== History ==
=== Background ===
Cleo Sertori was born on April 19, 1990, to Donald and Bev Sertori and grew up in the household with a younger sister, Kimberly (nicknamed Kim). Her father is a successful fisherman, but her mother's occupation is unknown. It is highly likely that Bev worked from home. Though Cleo and Kim rarely got along, the two sisters loved each other deep down. At the age of 5 years old, Cleo became childhood friends with Lewis McCartney, and they often studied together in school. As they grew older, Lewis and Cleo each began developing romantic feelings for each other. Whether or not Lewis had a crush on her first his unknown, but it is hinted throughout later episodes of Season 1 that she has been developing romantic feelings for him for some time. 
She later became friends with Emma Gilbert, who was her first best girlfriend. Since childhood, Cleo has always been afraid of the water and never learned how to swim. 
=== H2O: Just Add Water ===
=== Mako Mermaids ===
After graduation, Cleo lost contact with her friends Rikki and Bella and presumably went to live in America with Lewis. However, Rikki hopes to reunite her friends one day. When that day comes, Mimmi and Ondina tell Rikki that she and her are welcome to  be part of the pod because they are Mako Mermaids, too. 
== Personality ==
Cleo is initially a girl who is shy and awkward prior to her transformation into a mermaid. She is additionally afraid of water and unsure of head. However, when Cleo discovers she is a mystical creature, Cleo fears she will be a "freak" and that this will ruin her social life. She got further afraid of being a mermaid as she started developing hydrokinesis and nearly being exposed after being thrown into a swimming pool at Miriam's party. She grows even further disillusioned with being a mermaid as Rikki and Emma are the first to accept their new powers. However, Cleo, after being in the water to stop her dad's employees from going to illegal fishing grounds, she stops fighting it and immediately adapts into the ocean. After accepting her Mermaid self, Cleo becomes more confident in herself and her abilities. 
In a surprising twist, Cleo takes a job at a water park despite the risk of getting a drip of water on her. Emma finds this to be a bad idea. However, Cleo refuses to let her fear of getting wet control her life because they spend their whole lives about water. This inspired Emma to do her own party anyway, even though she planned on canceling it in fear of transforming. 
Cleo is also highly intelligent and graduated from high school at the top of her science class. 
== Physical appearance ==
Cleo is considered one of the most beautiful girls in high school, having brought the attraction of several major characters, such as Lewis, Byron, and Nate. Although this doesn't count as the time she was a siren and attracted boys to her house. She has long, wavy brown hair, brown eyes, and tanned skin. Due to living in Australia, Cleo mostly dresses for warm weather. In the first season, Cleo mainly wears dresses and sandals. However, as the show progresses, she starts to wear tank tops and pants more often. Cleo also mostly keeps her hair up in either a bun, braid, or ponytail. In seasons 1 and 2, Cleo wears an old silver locket with a medium-sized dependent that has a small blue jewel on top. The locket matches Emma and Rikki and were made by a man named Max, which he made the three original mermaids, Louise, Gracie (the one Cleo owns and Julia.) However in season 3, Cleo and Rikki start wearing a blue stone necklace on a black string to signify their relationship/friendship with Bella. The stones appear to be the same rocks that are used inside of a mermaid's moon ring, as seen in the spin-off, Mako Mermaids. However, the difference is that Rikki and Cleo's stones come from the Mako Island moon pool while Bella got hers from the Irish Sea caves. 
== Powers ==
Hydrokinesis
Aerokinesis
Combined Atmokinesis: With Emma's and Riiki's combined weather powers, Cleo can create powerful storms. On the first night their powers were enhanced, Cleo and her friends created a massive electrical storm over Mako Island that also was powerful enough to lift Lewis into the air and send him flying out of the Moon pool. The massive storm created was an electrical storm, with the wind being measured over 200 km/h, making it the equivalent of a category 4 severe tropical cyclone.   The girls later combined their advanced powers together and were able to defeat Charlotte with ease and make sure she lost her tail in the process 
Siren Singing (temporarily; formerly)
Moon Spell Control: Cleo also has a deep fear of the full moon controlling her, but midway to season 2, she gets control over the moon. To prove it, instead of acting strangely when she tried rescuing Lewis, Cleo, Emma and Rikki still retain their normal personality. By Season 3, she is no longer affected by the full moon, possibly due to her being a mermaid for so long and the fact that she learned to control it like a naturally born mermaid. 
Speed-Swimming
Enhanced Breath: Like other mermaids, Cleo can hold her breath underwater for 15 minutes. However, if she stays under the water too long, Cleo will go into stasis until she's brought back to the surface. When she was trapped in the fishing net, she lost consciousness until Emma and Rikki saved her. 
Thermal Resistance
Aquatic Adaptation: Cleo can adapt well to any aquatic environment.  When Cleo first swam in the ocean in "Catch of the Day," she panicked. She held her breath and tried to swim to the surface. However, her tail was weighing her down until she realized she now could hold her breath longer. She then learned how to swim with a tail fairly fast and controlled our
Limited Transformation: Cleo can transform into a mermaid; however, she can not will it on her own, as it is more of a passive power than an active one. She will grow a tail in water or liquid containing a certain percentage of water within ten seconds.  
Tower of Light creation (along with Rikki Chadwick and Bella Hartley)
Intelligent: Despite trouble, Cleo is an intelligent person. Whenever Rikki and Emma are fighting, Cleo remains neutral and acts as the voice of reason for them both. At the end of the series, she graduated with a biology Major or a Major in general.
Biology/Science: Cleo was initially an average student when it came to science. However, in season 3, Cleo developed an interest in science when Lewis left, mostly because it made her feel closer to him now that he was gone. At the end of the series, she graduated with a biology Major or a Major in general.
== Trivia ==
* Cleo is the second person of her friends to be a child of divorce, following Rikki. Lewis (presumably), Bella's, and Emma's parents are together, Zane's mother is absent, and it is implied that Will and Sophie's parents are deceased. However, Cleo is the first of the mermaids to have a step parent. This case is her stepmother, Sam. 
* Cleo, along with Will, Emma, and Lewis, are one of the main characters who has a sibling: a younger sister, Kim
* The actress who plays Cleo's sister Kim shares the same first name with her. 
== Navigation ==
Category:H2O characters
Category:Females
Category:Heroines
Category:Humans
Category:Merpeople
Category:Protagonists
Category:Characters with hydrokinesis
Category:Characters with weather-based powers
Category:Characters with prophecies
Category:TV show characters
Category:Nickelodeon characters
Category:Adults
Category:Teenagers
Category:Main protagonists