I know this isn't apart of this book but hear me out. Also I'm not completely caught up on this anime.
Tokoyami is the only one I know who has a quirk with a conscience. So what he he had a twin that 'died' in the womb.
For whatever reason his quirk before it completely manifested stored the twin inside it and completely combined the two.
This would be an expansion of why his quirk has a conscience.
Sorry if this doesn't made complete sense, I'm doing this fastly and before I forget it.
