A Servant initially summoned by Rin who later reveals himself as Shirou's future self. He creates the Unlimited Blade Works reality marble, kidnaps Rin, and duels Shirou before ultimately helping him defeat Gilgamesh and disappearing.
Rin initially commands Archer as her summoned Servant.
Rin performs the summoning ritual and summons Archer at the beginning of the Holy Grail War.
Archer functions as a future version of Shirou and the embodiment of his possible regret.
Shirou deduces that Archer is his suicidal future self, seeking to kill Shirou to end his own regretful existence.
Explore the full interactive character relationship map of Fate/stay night: Unlimited Blade Works