
The bully, I would disapprove of before and after knowing his background. If I was a classmate I would dislike him, if I was a parent I would ask my kid to stay away from him and to tell me if he tried to bother them and if I was a teacher, I would drag his ass to face disciplinary action and undergo counselling while also reporting his household to child protection services on the side. Regardless of his problems with his dad's wife, it does not make for a convincing reason to start bullying a random guy who has nothing to do with you and you have nothing to gain from. There is no reason for him to be triggered by the main character. I don't see how scary adult at home leads to a natural progression towards bullying random classmates and being a toxic bitch towards friends who've been nothing but angels to you. This excuse is what, a PG version of "my parents used to beat me so I turned into a serial killer, woe be me, it couldn't be helped"?
The main character, on the other hand, is someone I would be neutral to before he gets involved with that red flag and very sympathetic to his anger, frustration and resentment afterwards. That other guy's dad's wife is the unanimous villain but if we got a tragic backstory for her, too, would you switch gears, ignore the fact that she abused a child under her care and, I think, sexually harassed him, too, and start to like her as well? Will a traumatic background serve as an adequate "explanation" of her sins?
In real life, your standards should be stricter than for fiction. Someone doing you wrong isn't a get out jail free card that lets you wrong someone else.

I really appreciate your reply. And I agree with everything you said. I mainly phrased my original comment in a way so people thought about the mc's character more realisticly. I just felt no one really sees his faults anymore or at leasts mentions them and it bugged me so that's why I said that but no one replied to me lol... anyway, sorry I took so long to respond.
Curious on your guy's perspective. The world's not black and white ofc but I say trauma explains a person actions, not excuses it. I don't know why but I remember Cirrus being an asshole and then I completely didn't care later on in the story cause I understood him. My point is if they were real people would you dislike Cirrus or Skylar not knowing their background. I just think it's interesting how we walk past people and find them annoying but don't personally know them and so this story has me thinking about that I guess