Gilgamesh and Kirei are quite the infamous pair in the Fate series. The duo resembles malevolence that exists in mankind. It’s always fascinating to see them on screen, their presence is enough to depict that something bad is going to happen. The nihilistic ideals combined with the haughty arrogance were more than enough to make the audience immersed in their testament of truth and righteousness. But how did it all start, why did Gilgamesh side with Kirei and betray his original master Tokiomi Tohsaka?
Gilgamesh is one of the servants in the Holy Grail War. He is an Archer level servant and is the secondary antagonist of Fate Zero, first being Kirei Kotomine. In the Fourth Holy Grail War, he was summoned by Tokiomi Tohsaka through the fossil of the first skin ever shed by a snake.
Why did Gilgamesh side with Kirei?
From the very beginning, Gilgamesh found Tokiomi uninteresting and monotonous. He was fixated on only one thing, to win the war and even had a plan ready for that too. It became overly tedious for Gilgamesh to see him like that, nothing was going on and it seemed like a waste of time. On the other hand, there was Kirei Kotomine, a disciple of Tokiomi who was also an impartial overseer of the war and an Elite Assassin/Executioner.
Despite having a strong moral compass, Kirei in his early age discovered that he was only able to experience true happiness through others’ suffering. Thus he was on a journey of finding himself and the evil within him and that particular trait piqued the curiosity of Gilgamesh.
It was not long before he started to spend time with Kirei, instilling the idea of joyfulness, solace and how he can achieve both of them without repressing himself to be untrue to himself. All of this impacted him tenfold when a command seal got scarred on his hand by the Holy Grail. It was at that moment when Gilgamesh saw his entertainment and wanted to toy with.
Apart from being arrogant and prideful, he is also quite the manipulative and smart one. To make sure Kirei follows the path he intends him to, Gilgamesh lays out all the paths including the one which Kirei has been wanting to travel i.e. of being true to himself and accepting the evil in him. In the end Gilgamesh says that it’s upto him whichever path he wants to troddle upon. Pure genius.
The quest for entertainment
Gilgamesh longed for entertainment after being succumbed to tediousness and Kirei managed to do that with his nihilistic ideals and unhinged beliefs. He was repressing his true self for a long time, believing himself to be a human regardless of his eccentric trait of gaining happiness from others’ suffering. But after Gilgamesh cleared that obstacle, he was able to appreciate himself more. And now, this became entertainment for Gilgamesh, to see where does Kirei ends up.
In the culmination of these events, Kirei reveals that Tokiomi will use command spell to compel Gilgamesh to commit suicide to win the Holy Grail and make a wish for his benefit. To counter this, he proposes that Gilgamesh should form a new contract with him in order to safeguard his life and for the Grail, to which Gilgamesh agrees and Kirei backstabs his mentor in the mansion so that a new contract between a new master and servant can be made.
Again, if you look from Gilgamesh’s point of view, this was all entertainment for him, he was enjoying every ounce of it and was interested how Kirei will handle things from here on and that’s why he had no objection when Kirei killed his master. It’s all amusement for him because he knows that whatever might be the case, he will certainly emerge as a victor.
It was the unending desire and fascinations of Kirei that were amusingly beautiful for Gilgamesh. At the end of the Fourth Grail War, when they both were reincarnated, Kirei still remained as evil and fascinating as he was before, this time slightly more intriguing too because now he knew the reason for his existence but still thrived for more. And that’s the reason why Gilgamesh sided with Kirei this whole time, he sought enjoyment and Kirei was able to fulfill it in every manner possible.