Honestly, there are so many things that could be said about who the traitor is. I’m just gonna look at all the theories because I wanna see this from everyone’s perspective. The traitor theories that are most often mentioned (or as I have heard) are the ones of Kaminari Denki, Uraraka Ochaco, Asui Tsuyu, Kirishima Eijiro, Hakagure Toru, and Monoma Neito (at least, those are what I have heard).
Let’s look at the ones of Denki, first. People say that he is only acting dumb. That is a fair thing to say. But if you look at how he did on the midterms, he hit solid rock bottom (haha Kiri much? Jk I’m not a Mineta). Then he even went to Yao-Momo's for tutoring while the rest of his class was shoving it in that he was obviously a lot dumber than they anticipated. While that might seem like "acting," it was clear that he was pretty annoyed from the remarks of his classmates. Another reason being that he gets "high" on his lightening at the very beginning of the fights so as to not hurt anyone and so that he can be used as bait.
Then there is Uraraka. Reasons being that she made up her whole "I’m poor" backstory to get pitied so that Deku or any person would think that is was her because she gave them a reason as to why she was going to UA, then made friends with Deku and Tenya, two very capable students of UA. But she always fights in battle and she really fought hard for her family at the sports fest and passed out because of it.
There is also Tsu. Reasons being that she is never scared during attacks from the League of Villains (LoV) and then made friends with Deku, Uraraka, and Tenya, three very capable students of UA. But, like Uraraka, she fights in battle and protected Deku when he was about to be attacked in the USJ Incident.
There is Kirishima. Reasons being that he only acts all upbeat and friendly in order to gain the trust of the people of Class 1-A so that no one expects anything bad from him. But, in an interview, Horikoshi (the creator of BNHA) specifically said that he was a character meant to tie the class together with his cheerful and outgoing nature, so why would he be the traitor if he was meant to tie the class together and not tear it apart.
Then there is Toru. Reasons being, she can sneak around and spy on people very easily. She said that she was where Todoroki was during the USJ Incident, and he mumbles about the fact that he could’ve frozen her. There was a lot of ice. Then, during any fight, she is never seen fighting. But she does have a caring and kind nature. Honestly, there is a lot of evidence pointing against her and not for her.
The last is Monoma. Reasons being that he always picks on Class 1-A whenever he can so now Class 1-A assumes that Monoma watching them is just Monoma being Monoma. But he is not in Class 1-A so he cannot spy on them as easily. He is away from them most of the time.
Well, anyway, that is all I’m gonna write. Tell me what you think and who you think the traitor is and why!!:> ~Maindo