You are overhaul's kid and were sent to UA rather than prison as Nezu thought it would be a more entertaining punishment. You were put in the A class and your classmates were all scared of you/ignored you. Except for one.

Denki: "WHAAAAAT? They're a total cutie-pie! plus she looked lonely."

Sero: "Aren't you scared of what they could do to you?! They're Overhaul's kid! What in the name of all might were you thinking?!"