i don't really like the main ship (or any ship in this manhwa) but I really like this story, so if you're up for hearing a different opinion here's mine! Also, disclaimer #1: I'm not trying to justify, excuse, diminish or ridicule the gravity of any of Jinha's actions. disclaimer #2: this will probably be pretty long, so don't feel compelled to read and reply!
I don't think that Won or Jinha are perfect people; far from it, actually. Poor Jinha just got manipulated and broken through and through, and even if his actions are not perfect, he's literally the victim.
Won, on the other hand, is both the perpetrator AND the victim. you know when ppl say "the perfect victim doesn't exist"? Won is literally that. ofc nothing ever fucking justifies lying and manipulating and breaking ppl's minds, but he's literally gone through so much in his life that you cannot turn a blind eye to that.
He got abused by his father, then by his tutor, repeatedly, during his whole life. Physical violence, domestic abuse, rape, assault, psychological and mental violence. That shit fucking changes you for the worst. it's not justifiable, but it's a valid explanation for the awful person he's become. So, even if he's a villain, he's still a sympathetic character.
The brother, on the other hand... ugh. Just Ugh. You know why imo he gets triple the hate that Won gets? Because he fucking sucks and has no valid reason to actually suck!
We know Jinha is mentally broken; that's a valid explanation.
We know Won is fucked up and has been abused his whole life; that's a valid explanation.
We know the tutor and the dad are just fucking evil abusers; we can deal with that, they're just plot devices of sorts.
But the brother? the actual third character in the story? He actively made Jinha's life shit by exploiting the fact that he was so evidently their parents' favourite, he diminished Jinha's accomplishment and intelligence every chance he got, belittling and ridiculing him to his face and behind his back. He saw an emotionally vulnerable Won and he fully and intentionally took advantage of him because he could get a "good fuck" out of him, he saw the marks of the abuse on Won's body and not only did not give a flying fuck about them, he also COMPLAINED that he couldn't leave more, and to rub more salt in the wound HE ABUSED HIM AS WELL! "He likes violence", he says while literally choking him without an ounce of consent. He's the fucking worst. He has no reason to act the way he does, but does anyway because he is a fucking shitty person, and both Jinha and Won would totally be better and healthier people if he literally didn't exist (or if he was a better person). So yeah, I think this is the reason most people (including me) hate his guts more than anyone else, while still admitting that everyone is fucked up and deserves jail time and also a psychiatric treatments.
Yall in the comments really like the main ship and hating the brother like he's quiet literally is blind to the grey guys intention to get close to a little boy. He don't deserve that much hate he's also a character that just wants love. Yall should redirect to the tutor he started that weird shit