Fate/Stay Night

Rin tells Shirō that he will have to use a command spell and make Saber assault humans in order to regain her mana. When Saber is sleeping, Shirō is shown a glimpse of her past, learning that she pulled Caliburn from the stone and became king of Britain. Archer tells Shirō that Saber knew using her Noble Phantasm would result in her disappearing and did not plan to do so but used it because she chose to protect him over everything else. While Saber is still weak, Shirō is captured by Ilya, who gives him the proposition to become her servant, which he refuses. After Saber wakes up, she, Rin and Archer go looking for Shirō.