Theories

Bakugou

Listen to the way Mitsuki talks about her son and then most of this will make sense. The thing about Bakugou is that everyone just thinks he is a straight up jerk who only cares for himself. Well the thing is that isn't true. If you haven't noticed from the flashbacks that Bakugou used to be a kind out-going kid, well you haven't really been paying much attention. 

In season 3, after Bakugou got saved from the League of Villain's, we meet Mitsuki Bakugou after and the first thing she does is yell at him and tell him that he is weak. She also hits him and makes him bow down his head. Well he was probably abused by his mom when he was younger causing him to do it to other people to make them feel his pain. But the thing is he wasn't just abused physically it was also mentally. I know Bakugou call his mom 'old hag' but if she had been calling him 'brat' his whole life maybe that isn't so bad. People reflect off of what they see and this mostly goes for Bakugou.

Another thing about Bakugou is that his quirk is explosions. I know everyone is like " we all know this what's your point!" Well the explosions come out of his hands and when an explosion goes off, where it went off there are marks. So, what I'm getting to is that Bakugou's quirk burns his hands and that there are black stains on his hands from using it so much. The other thing about his quirk is that it is so loud. Like at this point he is probably almost deaf. But what is my point? My point is that no matter which way you turn it Bakugou gets hurt on a daily basis but doesn't stop no matter what. Why? The one thing I have noticed about Bakugou is that he doesn't like feeling weak. So, he would never stop using it even if he does get hurt.

Lastly, he has PTSD, or post traumatic stress disorder. How does he have that? Well the abuse from his mom is one reason but the other is when he got kidnapped by the LOV he got kidnapped from behind. Once he got back he never wanted anyone to walk in front of him and he says that it is his fault that he had ended All Might. As he said it "constantly played on loop in his head." That is one sign of PTSD that the same thing kept playing in his head multiple times and he couldn't stop it.