It's been years but recently, this show has been on my mind again and i think i finally have words to express how i feel about it.

Beomseok, rightfully, catches alot of flack but i also think alot of people ignore the context of the situation and reduce him to the sole cause of everything that happened.

I think all three friends messed up, they all had thier reasons and all three of them realized where they went wrong but reached a point where the damage was already done.

Lets start with Beomseok.

His sins are obvious. He betrayed his friends and turned into a major asshole who aligned himself with the worst possible types.
What ppl ignore though is, the situation he was in was one many ppl likely wouldn't have done better in.

Imagine, you spend your whole life being beaten, abused and looked down upon with the one person who was supposed to protect you, your parent, being the one responsible for alot of your pain.
You finally get friends, but due to your life experience, you can't bring yourself to feel fully secure in those friendships because of how you grew up and then when you finally get the chance to get revenge on some of the people who made your life a living hell and not feel as powerless, one of those friends not only stops you, but starts using force on you the same way everyone else in your life has because you're not venting your dislike for what they did and how they made you feel in a way they like.

Based on all of that, i don't think it should be hard to understand why Beomseok would begin leveling his anger at Suho, and it was only after the scene in the boxing ring that he finally realizes he leveled his anger at everyone who'd hurt him on one of his only genuine friends.

That brings me to Suho. Suho has alot of good traits, he's kind, loyal, he cares about people.

He, however, was still an immature teenage boy.

Stopping Beomseok, and even Sieun, from going at thier bullies was born out of noble intentions but also out of a lack of understanding of what it feels like to be powerless because he never had to feel powerless. He could take a moral stance in those situations because he had no emotional stake in them, Previously If someone opposed him, he could utilize force to make them do what he wanted and so he never felt what it was like to be someone else's punching bag, and that willingness to use force ended up being used on Beomseok, someone who spent his life being made to follow what other people said through force and violence.
He similarly also realizes where he went wrong during the Boxing Scene but he can no longer meaningfully stop the violence because Sieun being hurt makes it impossible for him to back down.

And finally, that brings me to Sieun.
Sieun was able to understand both sides and was the most mature but that maturity was paired with a lack of social interaction that made it hard for him to express himself properly, which led to where he messed up, inaction.

He knew Beomseok was likely acting out because he felt powerless and could relate to it, but he didn't have the ability properly articulate that to Beomseok to make him feel seen and he couldn't explain it properly to Suho to make him understand before things went too far.
Sieun's realization of where he went wrong comes in the end when he can't bring himself punch Beomseok, because as much as Beomseok fucked up, Sieun understands fully well why he did it and that they were in similar boats with the only difference being, Sieun had ways of fighting back and defending himself, Beomseok didn't.