Katsuku: The Fusion of Izuku and Katsuki

During their first Hero Basics Training class, a bright light appears and the two childhood friends fused. Permanently. Being a whole different person, and opening a vacant spot, Katsuku causes more headaches than Izuku and Katsuki would if they never fused. But not like that matters to Katsuku, since he's insane! And he'll drive everyone else insane too, author included.