you are a special child. Your quirk is that whoever drinks your blood will have 10X the power. But you had to be happy and calm for it to work. Everyone wanted that so the heirs locked you away in an isolated island where you were kept. You liked it there. No one really did anything to you. You got gifts everyday to keep you entertained.

later all for one heard about you. He thought that if Tomura drank your blood he would be an unstoppable villain. He sent Tomura and the league to get you

they killed everyone in the building and burst through the door to your cell

Tomura: hay

Dabi: About time we found them

Toga: this should be good!

Twice: you ready to come?