Because of a late quirk manifestation, you accidently killed your family. Now you were alone, a young child wandering the streets waiting for someone to help.. no one helped. They all looked at you like some sort of monster with the dry blood on your clothing.

You found yourself crying under a bridge, and suddenly someone approached you. All For One crouched down in front of you and held out a hand. “Poor child, no one to care for you...come, join me. I will take care of you." You looked up with admiration for him. He wanted to help you? Why? What a "kind" man.