Who's Katsuki Bakugō?

Set in an alternate universe where Katsuki was severely abused by his mother, he developed a dissociative disorder known as DID (Dissociative Identity Disorder.) As the original host, he can't remember any of his trauma and often believes his diagnosis is completely wrong. He spends most of his days in the inner world where it's safe and only fronts every few months to check in on his life.

Takashi is the current host. Only Deku knows about the alters; but what happens when Aizawa begins to suspect something is wrong with his top student?