Bnha:
Takoyami actually rarely sleeps at night because of Dark Shadow wanting attention and being harder to control.
Bakugou does want to be Deku's friend but screws it up every time he goes to redeem himself.
Mina is really an alien XD (not mind just thought it was amusing)
Denki just pretends to be dumb after years of people making fun of him.
Sanders Sides:
Virgil used to be happy but then he realized that the world was a bad place after the death of a friend.
Logan really does know how to use slang (sometimes) but chooses not too.
Patton is the youngest AU is funny
Roman really likes Ramen (almost as much as Logan likes Crofters)
My own:
Seaward (Tajes son) can turn into a dragon when angry only because of a secret dragonstone Azura hides in his armor.
Raven (Villian/hero OC) is not Bi but Pan and has no shame with it, I mean, she fell in love with Serra (Tajes Daughter) and before that flirted with literally everyone.
Raymond (Camelot SDS OC) is very shy but when he sees something bothering a loved one he is a complete different person, as he becomes a psychopathic killer.
Shae (Monster Musume 2nd gen) can use swords well but feels like she isn't good so she doesn't take action until needed.
You have any head Cannons? Tell me!