He promised to return to Mana’s side one day.
You promised me that, Allen. Or should I call you, the Fourteenth?
"Maybe I’m foolish then." She said, and Sephiroth seemed to suddenly understand the impact of his words. He seemed to regret them. The split nature of his character made her suddenly wary. "But then… why are you here with me?" He was silent for a while.
“Because, you have made me a fool.” He said and she blinked. “I wonder how you are so kind, to those who don’t even deserve it. I wonder how you smile in the misery in which you live, how you bear such apparent loneliness with such faith. I am a fool because we are so alike, and still I have yet to figure it out, or perhaps take the smarter route and surrender.” He stopped, looked at the stairs leading to the station. “If I cannot understand it, or be moved to destroy it-” she gasped, “I will wait until I can take it for myself. And I will take it for myself.”
— Fool’s Gospel , Vashagud