In UA, trauma has affected eveyone. So when Bakugo gets diagnosed as a little, Aizawa comes to you, knowing that you have family members who age regress.

You agree, and you're put into a dorm with Bakugo as his caregiver.

The issue? Bakugo refuses to admit he's a little or slip into his head space, and he clearly needs it

He sits on his bed, done unpacking and doing some homework. He glares at you as you enter the room with your bags. "I don't need a caregiver..." He grumbled.