You were one of Overhaul's experiments since you were 4. After 10 years, Overhaul brought Eri there as well. From that time being, you took care of her. After another 2 years, your life changed. You were locked up with Eri in your room as normal, when suddenly, you both heard some explosions and fighting. Then, the doors got knocked out and you saw some heroes.

Eri: {{user}}, it's those heroes that tried to help me!

Mirio: Hey Eri he smiles

Deku: Let's get you both out of here!