Diarmuid Ua Duibhne

, Class Name , is the Lancer-class Servant of Kayneth El-Melloi Archibald in the Fourth Holy Grail War of Fate/Zero. He is a chivalrous servant who wishes to do his best to serve his Master and obtain victory within the war for the Grail. He shares a bond of mutual respect with rival Servant Artoria, wishing to face her in an honorable duel to the death. 
He is one of the Servants summoned by Ritsuka Fujimaru in the Grand Orders of Fate/Grand Order.
==Profile==
===Identity===
Diarmuid is the son of , foster son of , and first spear of the knights of Fianna. He is known as , due to a magical love spot granted to him by a young girl. Any woman who gazes upon the spot instantly falls in love with him, which eventually leads to an encounter with Grainne, the bride of Fionn mac Cumhaill. Gráinne, having fallen in love with Diarmuid at her wedding party, placed a geis upon him to run away with her.
It has been said that, even while at large, Diarmuid stuck to his fidelity to Fionn and did not lay a finger on Grainne. They were pursued relentlessly by Fionn, but after much blood was shed, he decided to recognize their marriage, granted Diarmuid a proper title and land, and welcomed them back as subjects.
Grainne.jpg|Diarmuid and Gráinne ("The Tree of Love" sculpture of ), in Fate/Zero.
Diarmuid past fight.png|Diarmuid against his former comrades, in Fate/Zero.
DemonBoar.png| in Fate/Grand Order, illustrated by PFALZ.
Diarmuid death.png|Diarmuid's death in Fate/Zero.
Sometime later while hunting with Fionn, Diarmuid was fatally injured by a Demon Boar, the reincarnation of his half-brother. Fionn, who had the ability to transform spring water in to a powerful healing agent was with him, so he had no fear of death. Fionn only needed to walk a few steps to the nearby spring, but with jealousy and hatred towards Diarmuid on his mind, he spilled the water twice. By the third time he went to scoop water, Diarmuid had already succumbed to his wound.
The story of his tragic love affair with Grainne would later become the model for the story of Lancelot and Guinevere.
===Appearance===
Diarmuid is regarded as a remarkably handsome young man with quirky long hair combed backward in a rough fashion that has a strand hanging down his face. He wears a dark teal outfit, similar to that of Cú Chulainn's. due to their shared Celtic mythology.
Irisviel von Einzbern instantly notes that his features are capable of sweeping a woman's heart at a glance. It is described that the bold features of his face are the high bridge of his nose and his valiant eyebrow. His hard cut mouth marks him with a stoic air, but his eyes seem make his gaze even more brilliant. Takeuchi considers his charm point to be his droopy eyes and button of a mouth. He has a strong, attractive manly scent that rises from him.
She soon realizes his elegant air of beauty is somewhat unnatural. Even though his features are considered handsome, much of it comes from his spiritual power charming women due to the curse of his beauty spot.
===Personality===
Diarmuid is an extremely proud and noble knight who wishes to serve his lord to the best of his abilities. The geis laid upon him by Gráinne was taken by Diarmuid as a test of his pride. He never once blamed her for forcing it upon him, and he truly admired her ability to throw away her pride, title, and future for the sake of her love. He was constantly distressed by the fact that he betrayed his lord, and even as he died while Fionn did nothing, he did not blame his lord for his actions. Diarmuid believed that despite the cruel twist of fate that led him down this path, the days spent with his lord and his love were used to the fullest. Diarmuid sees the Holy Grail War as a miracle that will allow him to regain his pride as a knight by fighting noble battles and delivering the Grail to his Master. He sees no use in wishing upon the Grail, as simply being summoned has already half-fulfilled his greatest desire. 
Diarmuid adheres strictly to the codes of chivalry and upholds his pride as a knight to the fullest, steadfastly believing in honor during battle. While being pursued by the knights of Fionn, he refused to fight against his former comrades. Despite having been presented with several chances to kill either Artoria Pendragon and Kiritsugu Emiya, he refuses to do so due to the circumstances with which he can do so are against his code. During his battles with Artoria, he attempts to provide for the fairest conditions possible. His code and pride also forbids him to ignore evil. During the Caster Crisis, he even goes as far as to fight alongside Artoria, acting as her "left hand", after she suffers the crippling wound from Gáe Buidhe in order to be able to face her in battle again in the future. He is willing to go so far as to destroy Gae Buidhe, so as to allow Artoria to use her Noble Phantasm to destroy Gilles de Rais, simply because Gilles himself is a great evil that has to be wiped out, despite the fact that he himself has nothing to gain from it.
However, in the end his chivalry became his downfall as by having no wish for the Grail, and wanting to serve as a faithful Knight as possible. He unintentionally blinds himself to the fact that the Holy Grail War is a Battle Royale where the participants even Artoria herself would do anything to get their wishes granted and not an honorable battleground like he initially believe. With him only realizing this when Kayneth under a geis sign by Kiritsugu himself commands him to commit suicide, this realization causes him to snap as he starts to curse not only Kayneth and Kiritsugu but Artoria herself all but destroying his friendship with her. 
====Relationships====
;Kayneth El-Melloi Archibald
:If Diarmuid appreciated Kayneth's talents and experience, then Kayneth would have treated him with a much softer attitude. To Diarmuid's disappointment, Kayneth doesn't believe him in the slightest and constantly looks down on his pride as a knight. He constantly berates Diarmuid, believing that Diarmuid plans to betray him and take his fiancee, Sola-Ui Nuada-Re Sophia-Ri, by using his magical spot. He is also a coward who constantly make demands that would have Diarmuid betray his code and win by all cost. Despite his Master's distrust and lack of character, Diarmuid remains extremely loyal, though he fears that Sola-Ui's attraction to him will eventually cause him to betray his Master once more. He happens to be a submissive man as he constantly took abuse from his Master while offering little resistance to stop it.
;Fionn mac Cumhaill
:"Well if it isn't my king, Fionn mac Cumhaill! I can't believe we're going to fight together again. There is no greater honor! ...By the way, is the queen also... Never mind, it's nothing."
;Artoria Pendragon (Saber)
:"Oh? That's... I see. She's an ally this time? Then I shall rely on the sword of the King of Knights."Fate/Grand Order - Diarmuid's My Room voicelines.
;Alexander
:"Th-The King of Conquerors!? H-how in the world did you turn into that after ten years!?"
==Role==
===Fate/Zero===
Lancer is summoned by Kayneth El-Melloi Archibald in the fourth Holy Grail War instead of the Rider-class Servant, Iskandar, whose catalyst was stolen by Waver Velvet. The contract formed with Lancer is unique in that while Kayneth holds the Command Spells, the energy to materialize Lancer is maintained by Sola-Ui, Kayneth's fiancée. Lancer, on the orders of Kayneth, actively makes his location known in order to entice a battle, while Kayneth hides his location. Saber and Irisviel von Einzbern answer this challenge, and eventually Lancer attains the upper hand by successfully striking her with Gáe Buidhe.
Before their fight can continue, Rider interrupts the battle, then followed by Berserker, and Archer. Once Berserker begins to attack Saber, Kayneth orders Lancer to join him and finish her off. As it is against Lancer's code of honor, Kayneth uses a command spell to force him to attack. Rider, who holds similar values of honor to Lancer, decides to force Berserker to retreat, and threatens to face Lancer with Saber if Kayneth doesn't back down. Lancer is later berated for his actions, though Sola-Ui cuts it short by criticizing Kayneth for not actively participating. Lancer stands up for his Master, who is irritated by Lancer because he believes that Sola-Ui has become infatuated with him. Before the issue can be addressed, their base, Fuyuki Hyatt Hotel, is attacked by Kiritsugu Emiya and Maiya Hisau, who destroy the hotel's foundation and collapses it around the three.Fate/Zero - Volume 1: The Untold Story of the Fourth Holy Grail War, ACT.3Fate/Zero - Volume 1: The Untold Story of the Fourth Holy Grail War, ACT.4Fate/Zero - Volume 2: The Mad Feast of Kings, ACT.5Fate/Zero - Volume 2: The Mad Feast of Kings, ACT.7
When Kayneth and the other Masters are offered a reward of extra Command Spells for defeating Caster, Lancer is sent to kill off the magic-wielding Servant, who at the time is engaged in battle with Saber. With Saber's help, he is successful in dispelling Caster's monster army with Gae Dearg, but abandons his duel with her in order to rescue Kayneth from Kiritsugu. Rendered bedridden and unable to perform magic, the injured Kayneth is forced to hand over his remaining Command Spells to Sola-Ui, whose infatuation with Lancer has escalated to near-obsession. Lancer is uncomfortably disturbed by how his current situation resembles his past life.
Lancer plays a key role in defeating Caster, when the Servant summons a giant monster to wreak havoc on Fuyuki City. He willingly destroys Gáe Buidhe in order to remove the enchantment inhibiting Saber's abilities, allowing her to employ her full power and destroy Caster.Fate/Zero - Volume 2: The Mad Feast of Kings, ACT.8
Lancer returns to the last location where he and Sola-Ui were supposed to meet, only to find Sola-Ui's severed hand. Lancer returns to a displeased Kayneth, apologizing profusely for failing to protect Sola-Ui. He tries to ease Kayneth's displeasure by informing Kayneth that Sola-Ui is still providing Lancer with mana, meaning she is still alive. Kayneth remains furious and openly mocks Lancer, on top of threatening to use a Command Spell he obtained from Risei Kotomine to force Lancer's obedience.
Saber and Irisviel later confront Lancer to finish his duel with Saber, but both are unaware that Saber's Master, Kiritsugu, had already formulated a plan to eliminate both Lancer and his Master. They have an equal battle for a time, though Lancer is unsettled by the fact that Saber is simulating the injury from Gae Buidhe. He believes it is out of pity, but she corrects him in that fighting with honor is the only way to draw out her true strength.
File:Lancer was force to commit sucide by his master.jpg|Lancer was forced to commit suicide by his Master.
File:Diarmuid curse.png|Lancer curses the Holy Grail.
The battle ends when Kiritsugu, holding Sola-Ui and him hostage, coerces Kayneth into using his last Command Spell to force his Servant to commit suicide; Lancer is thus forced to drive Gáe Dearg into his own chest. The shocked Servant realises that he has been fatally betrayed by his current Master, just as his former master Fionn had caused his death during his first lifetime. Enraged with his one wish being denied again for others', especially his Master's personal gain, Lancer dies cursing the Holy Grail, Kayneth, Sola-Ui, Saber, Kiritsugu, and the world at large for his fate.Fate/Zero - Volume 3: The Scattered Ones, ACT.11
====Einzbern Consultation Room====
Lancer appears in the Einzbern Consultation Room, a metafiction segment analyzing the story, that takes place after he dies and becomes absorbed into the Holy Grail. Lancer has amnesia due to the mental trauma caused by the various events of the Holy Grail War, only remembering certain key parts that gloss over his misery. He enters the dojo believing it to be a school of martial arts that he can challenge, but he is told by Irisviel von Einzbern that they provide consolation. Student 0, temporarily falling under his curse, consoles him on not being able to remember his Master and his wife, telling him to forget his painful past, including his relationship with Grainne. Though she convinces him that he must have died nobly in combat against Saber, Lancer wishes to progress a proper and noble Grail war to a romantic relation with Saber. Irisviel, acting as an agent for the Grail's corruption, brings back his despair by making him remember the true nature of his death before being fully absorbed.
===Fate/unlimited codes===
Lancer appears as an unlockable character in Fate/unlimited codes. To unlock him, you have to unlock Saber Alter and Leysritt. To make him show up, you have to get at least three KOs with supers (if game is set to best of 3) before reaching stage 5. Beat Zero Lancer and continue clearing arcade to unlock him. He is known as with the title . Unlike the other characters, he lacks any sort of story mode.
He notes that it is an undeserved honor to receive the chance to take up arms again, saying that he will not let the chance go to waste. Should he defeat Saber, he exclaims that it was the conclusion he had sought, and that he is thankful for having the opportunity to challenge her once again. He also notes that it is an unbelievable honor to face Lancer, a memory he will cherish deeply.
===Fate/Grand Order===
==== Scáthach's Trial Quest ====
Diarmuid is summoned by Scáthach using Ritsuka's Magic Circuits to help them combat the remnants of those whose eras were incinerated by the Incineration of Humanity inside Ritsuka and Mash's shared dream. He helps them defeat the final remnant, an avatar of Artemis. 
==== Valentine Event: Chocolate Lady's Commotion ====
EMIYA calls upon Diarmuid to talk about the dangers of chocolate when he fails to convince Ritsuka, Diarmuid recounts his receiving of chocolate in a certain Grail War ended with two people killing each other and him with stomach ulcers. Ritsuka remains convinced, so EMIYA and Diarmuid decide to use brute force. 
After the fight, Julius Caesar appears and hints the mastermind behind the Choco-Servants is a recent Servant that he and William Shakespeare describe as a villain. He tells Ritsuka to chase after them but prompts EMIYA and Diarmuid to fight with him against Ritsuka after Ritsuka told him to stop eating chocolate. Afterward, EMIYA takes Caesar on a marathon run, with Diarmuid following.
 
====Fifth Singularity: E Pluburis Unum====
Diarmuid serves as a part of the Celtic army under Medb. He is partnered with Fionn mac Cumhaill, who constantly reminds him of his affair.
He and Fionn attack the rear base of the American Independence Army. Their soldiers are repelled by Ritsuka, Mash, and Florence Nightingale. The three defeat Diarmuid, but Fionn heals him and fights together with him. They’re forced to retreat when reinforcements from the Resistance arrive. Fionn tells Diarmuid to abandon their soldiers if they can’t comprehend the order to retreat. Before leaving though, Diarmuid tells Mash to consider accepting Fionn’s marriage proposal if he defeats her.Fate/Grand Order - E Pluribus Unum: The Grand Battle of Legends in North America, Section 2: Crimean Angel They return to the White House, the Celtic Headquarters, and report to Medb and Cú Chulainn Alter about their failure. After Cú Chulainn Alter warns them they won't get a third chance, Diarmuid and Fionn leave.Fate/Grand Order - E Pluribus Unum: The Grand Battle of Legends in North America, Section 8: My Fair Lady
The two confront Ritsuka’s party when they leave Alcatraz prison. Fionn reminds Mash of his marriage proposal. He and Diarmuid then fight the group; Fionn agrees not to let Mash’s beauty hold him back. Fionn asked Beowulf to join him, but he refused. They are defeated, and Diarmuid is left disappointed they couldn’t achieve victory. Fionn confesses to him he envied him, as he was trying to die for his love. The two then disappear together.Fate/Grand Order - E Pluribus Unum: The Grand Battle of Legends in North America, Section 12: Sympathy for the Soldier
==== Fate/Accel Zero Order ====
Diarmuid challenges Artoria Pendragon to a duel at the wharf. He goes there ahead of her and Irisviel, but he becomes trapped in El-Melloi II's Unreturning Formation. When the stone maze is disabled, he is left confused and confronts Ritsuka's party. El-Melloi II asks him to calm down while revealing his True Name and explaining they're not Kayneth's enemies. Diarmuid leaves with Kayneth after the latter agrees to meet with El-Melloi II later tonight.Fate/Grand Order - Fate/Accel Zero Order, ACT-2: Military Intervention
Meeting with El-Melloi II later that night, Kayneth and Diarmuid are both convinced by him that the Archibalds created Chaldea's technology thanks to Kayneth's leadership.Fate/Grand Order - Fate/Accel Zero Order, ACT-6: United Battlefront They then accompany Ritsuka's party to Gilles' hideout in the sewers. After Gilles is killed, Kayneth and Diarmuid leave for the church to retrieve an additional Command Spell.
Eventually, they meet with Ritsuka's party again. El-Melloi II convinces Kayneth that the war is a farce created by his family's enemies, the Trambelios, in collusion with the Tohsakas, to lure him away from the Clock Tower and increase their influence over the Association. Diarmuid is ready to accompany his Master to London to stop the Trambelios, but Kayneth, but Kayneth orders him with a Command Spell to stay and continue the Grail War for his family’s reputation. He then lends Diarmuid to the group for that purpose.Fate/Grand Order - Fate/Accel Zero Order, ACT-11: Strategist's Trap
The group meets up with Kariya later then disrupts the discussion between Artoria, Iskandar, and Gilgamesh to kill Gilgamesh.Fate/Grand Order - Fate/Accel Zero Order, ACT-12: Discussing the Holy Grail After Gilgamesh perishes, however, Lancelot attacks Artoria when Kariya collapses from expending too much magical energy. The group helps her fight Lancelot, but Iskandar soon stops the fight. He warns her and Diarmuid that they'll be his enemies if they ally with El-Melloi II. Diarmuid considers defeating Iskandar on Ritsuka’s order, but El-Melloi II reminds them they’re only allowed to defeat four Servants. After Iskandar leaves with Kariya and Lancelot,Fate/Grand Order - Fate/Accel Zero Order, ACT-13: Battle Royale EMIYA arrives to kill Irisviel. EMIYA is defeated in the ensuing fight, and he is convinced to join the others and go to the Grail's cavern.Fate/Grand Order - Fate/Accel Zero Order, ACT-14: The Shadow Chasing Irisviel
There El-Melloi II explains the Grail's corruption and is initial plan to safely dismantle the Grail. However, the plan was changed to destroying the Grail directly with the failure to recruit Iskandar. After defeating Hassan of the Hundred Faces,Fate/Grand Order - Fate/Accel Zero Order, ACT-15: To the Greater Grail the group moves on to Grail's chamber, where they defeat Iskandar.Fate/Grand Order - Fate/Accel Zero Order, ACT-16: King's Pride After he disappears, though, El-Melloi II is ambushed and rendered unconscious by Lancelot, now Zouken Matou's Servant.Fate/Grand Order - Fate/Accel Zero Order, ACT-17: Wish of the Three Founding Families The others kill Lancelot, but that, unfortunately, triggers the Grail's activation. Zouken uses Irisviel's magical energy to hasten the process. A figure resembling Irisviel called Black Iri then emerges from the Greater Grail and proceeds to devour Zouken. She then goes to devour the group, saying five Heroic Spirits aren't enough to fill her. Artoria and Diarmuid hold her off while the others escape.Fate/Grand Order - Fate/Accel Zero Order, ACT-18: The Fallen Grail
Unfortunately, she and Diarmuid struggle against Black Iri, but thankfully the others return to assist. Artoria recognizes Waver Velvet (who joined the group) has become a Servant, which unbeknownst to her resulted from becoming Zhuge Liang's temporary vessel. After the group destroys Black Iri, Diarmuid hopes to meet Ritsuka's party again, suspecting it'll be when the world's at stake before disappearing due to the Grail's destruction.
==== Summer Event: Chaldea Summer Memories ====
Diarmuid and several other of Ritsuka’s Servants are accidentally rayshifted to a remote island where they’re unable to contact Chaldea. He agrees with Fionn that the men should act discreetly with so many beautiful girls around to avoid troublesome incidents, noting that his liege understands himself well. When Cú Chulainn asks if the Fenian Cycle always begins with a skit, Diarmuid apologizes for his liege's behavior. He claims Fionn is only eager to deepen the bond with all the Servants here.
Fionn is the first to notice Blackbeard wash ashore when the latter returns from observing the island. Diarmuid thinks Blackbeard is someone who drowned at sea and drifted to shore. He considers giving him proper burial until Blackbeard regains consciousness. Blackbeard explains their location is still unknown, and it's nearly impossible to escape by ship. He then disappears in rage, cursing everyone for trampling on his dearest wish. Diarmuid strangely feels a deep affinity for him. After Scáthach alters the female Servants' Spirit Origins to give them swimsuits, Diarmuid denies Fionn's accusation that he'll use his Love Spot to his advantage.
At some point, Fionn, Diarmuid, and Cú Chulainn founded a secret village for the men.
When the crops are destroyed, Fionn uses Fintan Finegas to determine the culprit is a four-legged beast. He and Diarmuid then stand guard. But during their watch, they're both gored by a demon boar. Ritsuka, Mash, Scáthach, Artoria, Mordred, Kiyohime, and Marie Antoinette find them dying the next day. Artoria learns from Diarmuid that their killer was a boar before he disppears.
==== Event: Prisma Causeway ====
Diarmuid is a member of the Magical Gentlemen, alongside Blackbeard, the Phantom of the Opera, and Gilles. Unlike his fellows, he only wants to serve Magical Girls loyally.Fate/Grand Order - Prisma Causeway, Jade Gentleman - The Blood Tears
Ritsuka's party finds him in the Land of Snow and Honey, crying tears of blood as he tells all adult women to stay away. Diarmuid describes how deceptive and domineering adult women can be in contrast to Magical Girls' sense of duty and dauntlessness. A fight then ensues when he tells Mash and Chloe von Einzbern to never become adults.
====Final Singularity: Solomon====
Diarmuid is amongst the "E Pluribus Unum" Singularity Servants to aid Chaldea against the Demon Gods Pillar.Fate/Grand Order - Salomon: The Grand Time Temple - Act 06: V / Arsenal Halphas
==== Valentine Event The Bountiful Chocolate Gardens of Valentine ====
Diarmuid helps plant cacao trees to produce more chocolate, even though it unnerves him that is's for the “evil” ritual of Valentine's. He nearly criticizes Semiramis for it until he sees one of her dove familiars. Cú Chulainn orders him to make scarecrows with the materials he got from the warehouse before leaving.
Later, Diarmuid, Cú Chulainn, Vlad III, and Karna find themselves unable to harvest cacao plants crossbred with mandrakes thanks to its scream. Semiramis told them the plants must be harvested today, as they'll likely wilt by tomorrow. Cú Chulainn go gets Nero Claudius and convinces her to sing by saying music helps plants produce a greater yield. With Nero's song countering the screams of the cacao mandrakes, and their ears protected by runes, the Lancers are able to her harvest the plants. Everyone soon finishes and Nero leaves, satisfied that she could help. Karna however points out that they have another field to harvest. Cú Chulainn leaves to go get Elizabeth Bathory.
====Interlude====
===== Twin-Spear of the Rose =====
Diarmuid confesses a portion of his Noble Phantasms' power is sealed. Romani Archaman deduces Diarmuid sealed his Noble Phantasms himself either due to an error in the summoning or a subconscious effort. He, therefore, suggests diving into Diarmuid’s mental landscape to solve the issue. While Diarmuid rejects it, Ritsuka accepts it and the group enters Diarmuid’s mental landscape.Fate/Grand Order - Diarmuid Ua Duibhne's Interlude: Twin-Spear of the Rose 
There, led by Diarmuid, the group partially undo the seal on his Noble Phantasm after defeating the guardians of his mental landscape, the seal on Diarmuid’s Noble Phantasm is partially undone. Afterward, they proceed to Fionnl‘s castle. There the Knights of Fianna explain that Fionn is waiting for Diarmuid elsewhere.
After defeating the knights, the group confronts Fionn in the forest where Diarmuid died. Fionn accuses Diarmuid of being unable to truly get over his regrets and resentments over his death. He then reveals himself to be the manifestation of his resentment. Diarmuid defeats Fionn and accepts he holds some resentment towards him. Thanks to his decision to hold onto something precious to him, his Noble Phantasm is completely unsealed.
===Other appearances===
TMAPRIL 2015 YARIO.jpg|YARIO in TYPE-MOON April Fools' Day 2015, illustrated by B-suke.
In TYPE-MOON's April Fools' Day 2009, moon.cinemas.jp is a fake movie theater site listing a number of parody films:
*Lancer was featured in , a parody film of . Lancer is the son of Sola and Kayneth and the older brother of Waver Velvet, he loves his sister. The story is expanded in TYPE-MOON 10th Anniversary Phantasm comic. Diarmuid was insulting Iskander's lack of gift knowledge when Waver was gifted with a Saber figure. The discussion came to an end when Waver dived to save the figure. Diarmuid still doesn't approve of their relationship. He accidentally trips but he was saved by his mother and his mother was saved by his father.
*He was featured in .
In TYPE-MOON'S April Fools' Day 2015, Lancer is in a group called YARIO and is part of the Imperial Roma talent agency, his class is .
Lancer is called in Fate/GUDAGUDA Order.
==Abilities==
Although Diarmuid is normally summoned as a Lancer, he also qualifies for the Saber class. While his Saint Graph and performance would be higher in that class, so would its summoning cost.Fate/Grand Order - Diarmuid Ua Duibhne (Saber) profile It is likely that it was Kayneth El-Melloi Archibald's original expectation to have summoned him in that form. 
During the Fourth Holy Grail War, Diarmuid's Master was formed by a two-person team. Kayneth El-Melloi Archibald was in possession of the Command Spells, while his fiancee, Sola-Ui Nuada-Re Sophia-Ri, provided the Magical Energy supply. Diarmuid's energy backup was greater than Cú Chulainn's during the Fifth Holy Grail War. Thus, in terms of pure firepower, Diarmuid was stronger. However, this is while in Japan, where Celtic Servants don't receive a Fame boost. Should both of them fight in Ireland, Cú Chulainn would gain an edge over him. If Diarmuid used every ounce of his Strength, he would unleash as much Magical Energy as the lightning released by Iskandar's Gordius Wheel when it moves. 
===Combat===
Diarmuid Ua Duibhne's basic parameters are not particularly high, but he excels at using battle tactics designed to trip up enemies stronger than himself. In particular, he is the natural enemy of those Heroic Spirits that rely on the powers of their Noble Phantasms to fight.
On his right hand, Diarmuid wields the demonic spear Gáe Dearg, which is over two meters in length. On the other hand, he holds Gáe Buidhe, which is one-third the length of the other one. His swings cover a wide area, and their Strength and speed are equal to what would be achieved with both hands. Furthermore, because they are used with just one hand, Diarmuid can use unconventional moves that wouldn't be possible otherwise. Normally, a single spear has some limitations. Because of its long-ranged nature, a gap will inevitably appear between two attacks. However, in Diarmuid's case, he can use the shorter spear as a consecutive blow without using feints or leaving openings. 
Having the ability to attack both at long and short range simultaneously grants Diarmuid an advantage over opponents wielding a single sword. However, in Artoria Pendragon's case, she is capable of turning the situation back in her favor thanks to Invisible Air concealing the shape and length of her sword. Despite Diarmuid being capable of blocking all her attacks, he is unable to find an opportunity to deal a fatal blow, so he becomes exhausted after fending her off for a while. For this reason, Diarmuid was forced to reveal his own Noble Phantasms to gain an advantage. According to Sola-Ui Nuada-Re Sophia-Ri, Diarmuid's later decision to aid Artoria against Lancelot was correct. In order to defeat Lancelot, he had no choice but to team up with her. Taking into account that Diarmuid has good compatibility with Lancelot, Artoria and him working together would have defeated Lancelot with ease. However, Kayneth El-Melloi Archibald strongly disagreed with her. Having used his Master's Perspective to analyze Artoria's abilities, he determined that Artoria was completely beyond Diarmuid's capabilities, so he considered a failure having lost such a great opportunity. 
During Diarmuid's and Artoria Pendragon's rematch, the latter refused to use her right hand as a sign of chivalry. While this made her attacks lighter, the single-speared Diarmuid was still unable to land a single hit on her. Kayneth El-Melloi Archibald once again concluded that the reason for this is that Diarmuid was simply to weak, far more inferior to Artoria. Nevertheless, the battle between the two was more intense and fiercer than the first one. It was a direct confrontation with no plots or tricks involved. Driven by Strength and speed far beyond the realm of a Human, the two warriors surpassed the , approaching the . 
Gilles de Rais is able to fight fully-armed Diarmuid and one-handed Artoria Pendragon simultaneously. While the two knights are capable of killing hundreds of Gilles' summoned monsters, Prelati's Spellbook allows the latter to restore them indefinitely with its unlimited Magical Energy supply. Being forced into a battle of attrition with the odds stacked against them, Artoria decided to use Strike Air to open a path for Diarmuid to attack. 
During his fight with the Fairy King Ábartach, Diarmuid eventually confesses that he is unable to finish him off with his current Saint Graph. Mash Kyrielight also states that Ábartach shows no signs of disappearing, and that it'll be fiendishly difficult to defeath him.Fate/Grand Order - Diarmuid Ua Duibhne (Saber) Interlude: "Arrival of Twin Swords"
===Skills===
====Class Skills====
*Magic Resistance (B Rank): Cancel Spells with a chant below three verses. Even if targeted by greater Magecraft and Greater Rituals, it is difficult for them to be affected.
====Personal Skills====
*Mind's Eye (True) (B Rank): Capable of calm analysis of battle conditions even when in danger and deduce an appropriate course of action after considering all possibilities to escape from a predicament. 
*Love Spot (C Rank): A spell (curse) inherent of one's facial features which is cast as soon as the target looks at the user's face; a Mystic Face. Enchants those of the user's opposite sex with Magical Energy. It is because of this Curse that he is known as "Diarmuid of the Love Spot". A woman who confronts Diarmuid gains a strong love affection for him. Effects are similar to those of Charm-type Mystic Eyes. Avoidable with the Magic Resistance Skill. While Irisviel von Einzbern, a Homunculus whose Magic Resistance is higher than normal, is immune to its effects, an average woman would be enslaved Diarmuid at a glance. 
*Knight's Strategy (B Rank): A battle methodology in which one grasps the flow of battle and induces the opponent to make a mistake, even without being a match for him/her in strength. A Skill not for self-strengthening, but to invite a check failure for the opponent. Consists of composed observation powers to wager on a momentary chance of victory. During the Fourth Holy Grail War, Diarmuid was able to trick Artoria Pendragon multiple times, landing two hits with his Noble Phantasms.
**Blighted Love Flowing in Profusion (A Rank): Upgrade from Knight's Strategy in Fate/Grand Order.
===Noble Phantasms===
Diarmuid's first Noble Phantasm is Gáe Dearg, a long red spear that temporarily nullifies the effects of Magical Energy. This weapon grants Diarmuid a great advantage over Lancelot, as it can break through Knight of Owner's enhancements. Furthermore, it can also nullify the concealing effects of Artoria Pendragon's Invisible Air or the protection of her armor.
Diarmuid's second Noble Phantasm is Gae Buidhe, a short yellow spear that inflicts cursed wounds that cannot be healed. Gae Buidhe was unable to take down Fairy King Ábartach.
In combat, Diarmuid can wield his two Noble Phantasms tightly wrapped in amulet cloths from their tips to the handles. The cloths seal their abilities and act as a counter-measure to avoid revealing their True Name. Nevertheless, their abilities will begin working immediately after undoing them from their bindings.
===How to win the Fourth Holy Grail War===
Depending on Diarmuid's strategy, he could have either won the entire Fourth Holy Grail War or suffered a humiliating defeat at the hands of Hassan of the Hundred Faces. The reason for Diarmuid's downfall during the events of Fate/Zero is that Artoria Pendragon's serene beauty and grace kindled his sense of chivalry. Had Diarmuid never crossed paths with her, his Master Kayneth El-Melloi Archibald could have persuaded him to excute his tasks as "dirty chores" that had to be completed no matter the cost without the hindrance of his honor or pride as a knight. Had these conditions been met, Diarmuid would have undoubtedly obtained the Holy Grail following the next tactic. In a battle, missions would be considered accomplished if Diarmuid scored one hit with Gae Buidhe. By repeating this tactic over and over again, he would exhaust all Servants enough for Lancelot, who has good compatibility with all of them, to take them out. Once Lancelot was the last enemy standing, he could be defeated by Diarmuid.
==Development==
Toshiyuki Shirai (Animator Director) first debut in episode 16. His young and vivacious pen draws Lancer and Saber's lively battle, as well as the anguished expressions on Lancer and Kayneth's faces. He said the plan for Lancer's scene was to have him turn into particles of light and fade away. But since he was the type of person who would have cursed everything as he died, Toshiyuki changed it so that he would be enveloped in black mist and crumble away. Even though it was a last-second change of plans, he said it was thanks to the staff who churned out terrific elements, it ended up being a memorable scene.
Ryuji Higurashi said Zero Lancer was a lot easier to draw than Lancer for the Fate/unlimited codes.
In the first draft of the British Lostbelt, Diarmuid was planned to appear as Cnoc na Riabh's second in command.Avalon le Fae Synopsys - Translated by Comun
===Creation and Conception===
He was a rare character to write for Gen Urobuchi because he normally views beautiful characters as either evil or stupid as an ironclad rule following that, if a man is too beautifully formed, his life would become truly miserable.
Kinoko Nasu carefully picked out the tragic Celtic hero. It surprised him that Urobuchi, who faithfully followed the beginning of Fate/stay night's story where Saber beaten the Lancer at the start of the story, but he also copied its ending where Lancer committed suicide.
He was designed by Takashi Takeuchi as having the manner of an English rocker.
Atsuhi Ikariya was in charge of the character design for the anime version.
===Reception===
Takeuchi calls Lancer as the faithful dog while Kayneth the stubborn man.Fate/Zero Blu-ray Disc Box I, p.030
 (Voice actor of Lancer) said Lancer had quite a few of scenes, but he was struck by the scene where he curses them as he dies (episode 16), and by the way he's shown as being so vigorous in the first half of the episode. He was so lively that when he's forced to kill himself, you feel sorrier for him. Midorikawa thought his suicide scene was handled delicately. There's an illustration for that scene in the original (the TYPE-MOON VERSION). But they presented it differently in the anime. Midorikawa was really impressed at how well they pulled it off. Midorikawa wished that they allow Lancer and Saber to go on fighting forever as Lancer seemed to be enjoying himself.
 (Voice actor of Kayneth) said that if team lancer had applied themselves, they would have been the favorite to win the Holy Grail War.
Toshiyuki Shirai said Lancer was really popular at Ufotable, with his, "I'm glad I met you!". He was nicknamed "Sparkling Lancer," and the day after he finished the keyframe art, copies would be posted at the animator's desks, and some of the girls even added world balloons that made him say "My Master!"
*In the Type-Moon's 10th Anniversary Character Poll, Lancer was ranked 28th.
==References==
Category:Characters in Fate/unlimited codes
Category:Characters in Fate/Zero
Category:Servants
Category:Humans
Category:Lancer-class Servants
Category:Characters in Fate/Grand Order (Part 1)
Category:Knights of Fianna
Category:Brynhildr's Beloved
Category:Irish Servants
Category:Heroic Spirits
Category:Lawful Neutral Servants
Category:Earth Attribute Servants
Category:Rider-class Servants
Category:B rank Strength Servants
Category:D rank Mana Servants
Category:A+ rank Agility Servants
Category:E rank Luck Servants
Category:C rank Endurance Servants
Category:B rank Noble Phantasm Servants
Category:Introduced in 2006
Category:Voice - Hikaru Midorikawa
Category:Fenian Cycle (topic)