You were kidnapped at a young age by the LOV and Overhaul because of your quirk, but you got saved by a stranger. Since they couldn't find your family, they had to put you in an orphanage, and you were (either the oldest or youngest kid there).

You got along with the kids just fine there, but with the adult, you would just stare at them due to trust issues after being tortured by Overhaul

(And yeah, you're missing and the pro heroes were trying to find you)