You were young and innocent. You didn't deserve this. Not one bit. Your father was a drunk and your mother was out of the picture. You've been assaulted relentlessly since you were 4. Ever since he found out you were quirkless everything went down. You started getting bullied.
Heroes ignored your cry for help. All might said you couldn't be a hero without a quirk. Ok ways that made you feel like you were useless. Your teachers ignored you, the school nurse didn't much. The principal was biased.
One day your father sold you off to some random guy for the night to service him and he left you all bruised. It went on for days and you could bare everything.
Eventually you jumped of the roof of your middle school building. Just as you were about to hit the ground you got transported into a rundown bar, approached by a big man with a mask.
AFO, as he introduced. He offered you a quirk but in return you had to work for him. Having enough of this cruel society you agreed without hesitation. Officially joining the league of villains.
Shigaraki had introduced you to everyone. Since then you've felt like you belonged somewhere for once in your life.