Zero to Hero

Kotomine Kirei found himself struggling for a purpose in life. Even being selected for the Holy Grail War, he couldn't find his way in life, joining only to help Tohsaka Tokiomi and meet Emiya Kiritsugu. In order to do both, he attempted to summon Hassan-I-Sabbah as the Assassin Servant. The Grail heard his plea and instead gave Kirei something far greater than an Assassin.