Berserker (Kariya Matou)

Berserker is the Berserker Class Servant in the Sixth Holy Grail War of Fate/Cruelty. He's unique because years before this war he served as the Master of Berserker in the Fourth Holy Grail War of Fate/Zero. During the war Berserker's Master is Rin Tohsaka of the Tohsaka Family.

Identity
Berserker is unique among Heroic Spirits because, instead of being a famed hero or villain from history, he was instead a previous master in the Holy Grail War. His true identity is that of Kariya Matou of the infamous Matou Family, and he served as the master of Berserker during the Fourth Holy Grail War of Fate/Zero. He was born as the younger brother of Byakuya Matou; however, four years prior to the Fourth Holy Grail War he severed ties with the family out of disgust for them, mainly for Zouken Matou himself. As a child he was good friends with Aoi Zenjou due to a planned forced marraige between the two of them, and he eventaully developed genuine feelings for her. However, after abandoning the Matou Family Zouken set her up with Tokiomi Tohsaka instead. He returned to visit a year before the Fourth Holy Grail War, only to find out that one of their two daughters, Sakura Tohsaka, was givern to Zouken so she could become the head of the family later on; Kariya and their two daughters, Sakura and Rin, always got along, and Kariya loved them as if they were his own daughters. Disgusted that Sakura was now in Zouken's care, he confronted him to get her back, and Zouken made a deal with him; in one year's time, he is to become a Master in the Fourth Holy Grail War and acquire the Holy Grail for him, and if he succeeded Zouken would return Sakura to her rightful family. Although Zouken never intended to do so, never believing that Kariya would succeed to begin with, Kariya agreed to his terms, overcome with desparation. Zouken inserted his family's Crest Worms inside of Zouken's body allowing him to use a bit of Magecraft; due to abandoning the family years ago, he was never trained in Magecraft like most of the other Masters in the war were. As soon as the war began he summoned the Berserker Class Servant and became his master, and then set out on his journey to acquire the Grail.

During the war he had very little action, doing mostly what Zouken Matou ordered him to. One notable action of his was his confrontation with Tokiomi Tohsaka whom he rideculed for giving up his daughter, and then tried to kill him, failing horribly. However, before he died, he was saved by Kirei Kotomine who saved his life, albeit being only for his own personal reasoning regardless. Over the course of the war he ended up being overcome by the Crest Worms inside of his body, and despite his determination and willpower, he eventually died at their hands. Even though he shouldn't have been able to become a Heroic Spirit, instead of making a contract with the "World" Angra Mainyu instead sensed his hatred and reached out to him, allowing him to make a contract with that dark spirit instead. Angra Mainyu managed to penetrated the frabric of time himself and send Kariya to the Throne of Heroes without the "World's" help. Kariya's wish to make this happen was that he wanted to rid the world of the entirety of the Matou Family once and for all. This all happened at the moment of his death, but it took twenty years before he would actually be summoned, during the Sixth Holy Grail War when the New Grail surfaced in Fuyuki City. At that time he would be summoned by Rin Tohsaka, whom he loved when she was a little girl, who unknowingly summoned him thanks to a pendant around her neck that she had on her that Kariya gave to her years ago. He was summoned as a Berserker Class Servant due to his hatred getting so far along that he went completely insane and uncontrollable for awhile.

Appearance
Before and during the Fourth Holy Grail War he wore a blue hoody and black trousers. Unlike his brother or nephew, he had black hair and black eyes. After he was implanted with Crest worms, half of his body was twisted and distorted.[3] He had a sickly pale skin complexion after his transformation. Half of his face had veins popping out and when Kariya used Magecraft, crest worm is seen squirming around his face. His hair turned completely white and one of his eye became blind. He was usually seen wearing his hood to cover his face. Rin compared his physical appearance to a cancer victim before collapsing in the original Fate/Zero novel. He lost function to his left leg and he was usually seen limping while walking. After being summoned as a Berserker Class Servant during the Sixth Holy Grail War of Fate/Cruelty, he wore a black cloak for the majority of the war, which covered the majority of his body except for his hands and feet. When his true appearance was revealed to Rin, he looked exactly the same as he did during Fate/Zero except both of his eyes were extremely large, and glowed a demonic red and black.

Personality
Kariya is a benign person whose reason for originally leaving his family was out of disgust for their horrible and inhumane practices.[3] He was willing to give up on pursuing a romance with Aoi because he genuinely loved her, and initially thought she would be happy with Tokiomi. He is shown to be good with children with both Rin and Sakura taking a strong liking to him, and he in turn, loves them as they were his own children.

Kariya also displayed a strong determination and a remarkable capacity to endure pain and suffering after Crest Worm implantation. Due to Crest Worms also slowly eating away at his body, particularly his brain, and the constant pain he has to endure, Kariya also becomes unable to perform complex thinking, and causes him to be easily manipulated by others as a result.

Though he genuinely wishes to save Sakura and help Aoi, he is unable to understand that despite giving Sakura away, Aoi still truly loves Tokiomi and she does not want him and Kariya to fight. He begins solely with the objective of rescuing Sakura and defeating Tokiomi, but diverges towards killing Tokiomi in order to save Aoi from her "suffering" and making Tokiomi's family his own. He bases his actions on his ideal fantasy for himself and his "family", and it becomes harder for him to rationalize his ambition as he comes closer to death.

After being summoned as a Berserker Class Servant to Rin Tohsaka he regained many of the same insane traits, although Rin being his master managed to qwell his anger and hatred a little bit every now and then, while under any other Master it probably would have been next to impossible, if not completely impossible. He's stuck between wanting to kill the revived Zouken Matou once and for all and protecting Rin, and eventually has to choose between the two, a choice that nearly kills him inside.

Development
Kariya's design was only drafted as planning for the publication of the first volume of Fate/Zero was beginning, so it went through major changes. The initial design was meant to give off a more villainous first impression, but it was eventually changed to the final design. Gen Urobuchi thinks that having the design obscure his eyes with the hood of his parka ruins his image a little by not showing enough of his "amazing face." Takashi Takeuchi believes that his appearance before becoming disfigured is too plain to even have him draw concept art of it. Kariya's regular face is without much individuality, much like that of generic protagonists in early games that begin with "Please enter your name", and the normality that can be seen in both his regular and twisted face is his true nature.[1] Atsushi Ikariya was in charge of the character design for the anime adaption.[3]

Fate/Zero
One year before the Fourth War, Kariya discovered that Sakura, who possessed a greater potential to become a strong magus than either Kariya himself or his brother Byakuya, had been handed over to the Matou family. Because Magi families traditionally raised only one child as an heir, Tokiomi had agreed to Zouken's request for his youngest daughter, supposedly for the intention of reviving the Matou family's stagnant bloodline.

Enraged at Tokiomi's treatment of his daughter and the grief that it caused Aoi, Kariya made a deal with Zouken: Kariya would participate in the 4th Holy Grail War and win the Holy Grail, which he knew to be Zouken's primary design. In exchange, Sakura would be allowed to return to her family. However, because Kariya lacked any formal training as a Mage, Kariya insisted on implanting numerous Crest Worms into his body. The worms would literally eat away at their host, causing Kariya's health to progressively fail, in return for significantly expanding his magic circuits and magical potential. By the time of his summoning of a Servant, Kariya's hair is white and the left side of his face and body paralyzed with many other complications. However, despite the Crest Worms and his own accelerated training, Kariya remained severely lacking as a magus. At Zouken's behest, he compensated for this by summoning a Berserker-class Servant, using the Mad Enhancement trait to boost his Servant's strength.

During their first two battles, Kariya's hatred for Tokiomi leads to his focusing solely on dispatching Tokiomi's Servant, Archer. Both attempts end in failure, due largely in part to Berserker's obsession with Saber leading him to engage her against his Master's orders. Berserker is struck down from behind by Rider in the first instance, and Archer in the second. Kariya's attempt to engage Tokiomi directly also ends badly, when the former is thoroughly out-classed and left for dead. His problems are further compounded by his failing health and excruciating pain, due to the high mana requirement of manifesting a Berserker-class Servant. After his defeat to Tokiomi, Kariya recovers from his serious injuries with the help of Kirei Kotomine, who secretly heals him without his mentor Tokiomi knowing.

Following the defeat of the rogue Caster, Kariya is again approached by Kirei Kotomine. In return for kidnapping Irisviel von Einzbern using Berserker in the guise of Rider, he is promised victory and the Holy Grail. To this end, Kirei replenishes Kariya's spent Command Spells with reserve seals he acquired from his murdered father. Kotomine's promise amuses Zouken, who sees through the priest's deceptions and reveals that he had never expected Kariya to win the War in the first place.

Kariya confronts Tokiomi, only to find him already dead, seconds before Aoi walks in on him. She misinterprets the situation, and in her grief blames him and the Matou family for taking away both Sakura and her husband. She accuses Kariya of never having loved anyone, completely oblivious to how he had always loved her. This breaks Kariya's heart and his resolve, revealing that he endured it all for her sake in the first place, and in utter frustration and disappointment, causing him to blindly lash out and strangle her in a moment of temporary madness. It is later revealed that the entire incident had been orchestrated by Kirei, whose sole intent was to derive amusement from it. Kariya then suffers from a psychological breakdown and cries out hysterically as he leaves the church, believing he murdered Aoi.

On the last day of the 4th Holy Grail War, Berserker faces off against Saber, culminating in a battle so ferocious that Berserker draws more mana than Kariya can provide. His Servant killed, Kariya survives long enough to make his way back to the Matou estate, where he is able to freely enter due to Zouken going to the area where the Grail was destroyed to obtain the pieces of it that he later implants in Sakura.[4] Kariya is approached by Sakura upon entering the basement. He tells her that he has come to rescue her, but collapses at her feet soon after. Kariya dies with a satisfied smile, comforted by dreams of escaping with Aoi, Sakura, and Rin and starting a family together.

Fate/Hollow Ataraxia
Kariya, alongside Byakuya and Zouken, were mentioned by Shinji, saying that they all sulked about their lives because they were Matous. Shinji simply refers to Kariya as "my father's younger brother".

As a Master
Kariya did not receive childhood training in magecraft unlike many of his opponents in the Fourth War, thus leading him to be one of the weakest Masters, only beating Ryuunosuke Uryuu for skill or experience. To his advantage however is the unique nature of the Matou Crest Worms. Allowing him to be forcibly injected with prana and spells, the Crest Worms transformed Kariya into something of a glass cannon magus. While his body became incredibly weak and easily broken, he gained the ability to fight using an evolution of the Crest Worms called Blade Wing Worms (翅刃虫, ?), carnivorous flying insects that strip flesh like piranhas.[3]

Kariya's Servant, Lancelot, is a Berserker-class servant. Much like all previous Berserkers, he requires many times more prana than regular Servants in order to remain materialized. Due to Kariya's fragile state of health, every single one of Berserker's fights leaves him in excruciating pain and brings him even closer to death. Despite his lack of training, his Master aptitude is extraordinarily high for a makeshift magus, which would have allowed for him to support Lancelot in a different class quite well. Kariya displays remarkable fortitude even with the absolutely absurd magical energy consumption, his goals of killing Tokiomi Tohsaka and saving Sakura, all for the sake of Aoi, his true motivation, allows him to keep going physically and to dominate Berserker's will with his own to force the rampaging Servant to focus on Gilgamesh. It could be said that he should be praised for enduring as long as he did during the War.[5] Due to the strain from Berserker draining his energy at the end, it killed all of the Crest Worms in Kariya's body, indicating to Zouken that he was doomed.[6]

As a Servant
When Kariya is summoned as a Berserker Class Servant during the Sixth Holy Grail War he's obviously a lot more powerful than he was as a Master. He still retains all of his magecraft abilities, which are greatly enhanced to the level of a Grandmaster due to the Mana levels of his master, Rin Tohsaka; this is very unique for a Berserker Class Servant, making him the second strongest Servant in the entire war, second only to Saber herself, of course.

As a Master
As a Master during the Fourth Holy Grail War of Fate/Zero, Kariya's Magecraft was sorely lacking. Due to abandoning his family many years prior to the war, he wasn't given specific training on Magecraft like most of the other Masters during the war were, and thus could only produce lack luster spells. Because of this, Zouken Matou infused his families Crest Worms with his body, which gave him the ability to use high levels of Magecraft, at the expense of his own life force.

As a Servant
After being summoned to the Sixth Holy Grail War by Rin Tohsaka, his Magecraft was extremely more advanced, without having to risk his own life force. This was due to him gaining complete control over the Crest Worms after the events of Fate/Zero. The Crest Worms contain extrordinary Magecraft powers, but only if one can master them completely. Becausde of this, Kariya is the only Berserker Class Servant in the history of the Grail Wars who is also a master of super high level Magecraft, to the point of topping the heads of the Three Families and even most Caster Class Servants.

Worms
Kariya's Noble Phantasms all have to do with the Crest Worms, due to the Crest Worm Torture that Zouken Matou put him under during the Fourth Holy Grail War.