Berserker served as Illyasviel's Servant during the fifth Holy Grail War. He is extremely loyal to and protective of Illyasviel. His class attribute has robbed him of rational thought in return for more power.
As a Berserker class, Heracles is exceptionally powerful in melee combat but lacks ranged attacks. He is also extremely durable and has sharp combat instincts which allows him to sense and react to danger. In return for his tremendous boost in power, the Master will experience an incredibly high demand in magical energy consumption to fuel Berserker.
Heracles is the greatest hero in Greek mythology, a half-god half-human born of Zeus and an unnamed human woman. Although incredibly talented, Heracles had anger issues. He was made to live as a shepherd to calm his anger. After that, he accomplished many great deeds. The King of Thebes gave Heracles his daughter, Megara's hand in marriage. She bore him 2 children and he earned the right to succeed the throne.
Zeus' wife, Hera disliked Heracles and took every opportunity to spite him. First, she drove Heracles insane, causing him to kill his wife Megara and his 2 children. He wished to repent for his sins and received a sign to do so by serving Eurystheus, the man who robbed the throne. Eurystheus gave Heracles the 12 labors. The number was initially 10, but Eurystheus did not accept the fulfillment of 2 of those, so he added 2 more.
Heracles managed to complete all 12 and was freed from his servitude to Eurystheus. The gods also blessed him with immortality. Hera was still angry at Heracles and cursed him with madness. Heracles' life ended by being poisoned by one of his wives. The gods approved of Heracles' great deeds and prepared him a seat in Olympus.
Berserker was summoned as Illyasviel's Servant for the fifth Holy Grail War. Heracles was chosen to give Illyasviel the greatest chance at winning the war. His immense power in addition to the Berserker class' power increase caused Illyasviel great pain.
Illyasviel and Berserker ambushed Shirou soon after he was briefed about the war by Kotomine. Illyasviel freely revealed the identity of Berserker and announced that she will win the war. Berserker easily overpowered Saber but Shirou took his last blow in her place. Illyasviel was shocked by his foolishness and left.
Later, Illyasviel kidnapped Shirou. Rin, Archer, and Saber came to rescue him but Illyasviel sent Berserker to stop them. Archer dueled Berserker to allow the others to escape. Archer managed to take off 6 of Berserker's lives which shocked Illyasviel.
The next day, Illyasviel and Berserker found the rest. Rin took off 1 of Berserker's lives and Shirou and Saber took off another 7, defeating Berserker. He praised the power of Shirou's projection of Caliburn before he disappeared.
Unlimited Blade Works
Illyasviel and Berserker ambushed Shirou like in the Fate route, but Saber brought the fight to a nearby graveyard which gave her terrain advantage because Berserker was too big to navigate between the tombstones. Archer fired Caladbolg II, severely damaging Berserker. Illyasviel then retreated, acknowledging Archer's power.
Much later, Shinji and Gilgamesh assaulted the Einzbern castle in order to capture Illyasviel. Gilgamesh repeatedly rained swords down on Berserker, then bound him with Enkidu before he was finally defeated.
Zouken, True Assassin, Saber, and the black shadow assaulted Einzbern castle. Saber and True Assassin defeated Berserker and he was devoured by the black shadow.
A few days later when Shirou and Kotomine went to Einzbern castle to rescue Illyasviel, the shadow sent a corrupted Berserker to attack Shirou. Being corrupted also robbed Berserker of his sight. Shirou projected a copy of Berserker's weapon and copied Heracles' technique, the Nine Lives Blade Works and defeated him with it.
A sword made of rock that Berserker wields.
It was part of the foundation of a temple and was used as the catalyst to summon Berserker.
A powerful defense that grants him 11 additional lives and immunity to attacks that are ranked as less than A-grade.