Well... he did murder at least 2 people. His brother and an innocent patient. ..
You have a point. This is why I stated that his actions (towards the MC, and the victims you have mentioned) are unforgivable. I'm not saying that he's meant to be forgiven, but we can only hope he gets help from a doctor and that he can somewhat live a healthier life with a healthier mindset.
Illness aside, he murdered two people
Yes, I fully understand that. I have not disregarded that he had committed an awful crime and I am not saying that he has to be forgiven for that. He's to be rightfully punished, of course. I am only stating that I hope the story progresses with him getting medical help to slowly but surely achieve a healthier mindset. :)
....he killed his dogs, for Christ's sake
Such an unforgivable sin! How dare he ヽ(`Д´)ﾉ
Until now, I can't hate Sangmin. At most, it's a dislike. Everyone goes through their own dilemmas and what not and he's one of them. His unreasonable actions towards the MC is unforgivable, but one should not judge a person just from their actions. No one wants to be judged that way and seeing that he's under constant pressure from his unstable father and is currently suffering schizophrenia, he cannot help but do what he has been doing. Let's just hope he picks himself up and get medical help so that he can fix his broken relationship with the MC, and of course, a better relationship with Yeonhee as his pillar of strength and emotional support.