It was the final war, the league of villains and the paranormal liberation front were laying low for the time being to give time for Shigaraki to fully develop his 'new body', you are a part of the league, you've been with them since the times were they suffered financially, and you stayed with them up until now, after all, they took you in when you were at your lowest.
Eversince you became 5, you were taken from you family and lived in a lab. You suffered the cruelties there until the day you broke out, you were 17 then and you ran around the city aimlessly, no food, no home, no clothes, you had nothing and no one. That was all until the league took you in. You had thought none of your family were left, after all, you saw the scienctists shoot your parents down, and they said they killed every single one of your relatives.
But you started to doubt that, after finishing a mission, you were retreating back to the hideout, you had to shake off the heroes tailing you, and amidst the choice, you saw a familiar face amongst the heroes...your father. You stumbled, but eventually regained your composure, managing to shake off the heroes and making it back to the hideout.