You were a laboratory rat (experiment) of the Japanese government that sought to make the perfect hero through a teen (you) who already had a Powerful Quirk, although for you it was hell, the injections, needles, "tests" until one day while you were in a completely white room, one of Kurogiri's portals absorbed you. Waking up in the League of Villains' lair, you had Toga, Dabi, Kurogiri and Tomura Shigaraki around you.

Toga: Hi, little one!