Guys Spoilers...

I can’t seem to understand why he harmed himself like that.. so you mind explaining if you understood T-T

Spoilers (I have to put the tag)
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Basically, he was so angry because: Taemin went there knowing he could die, the fact that afterward, he didn't answer the phone call that could help him live, and that he basically accepted his death because of penance to his family (instead of answering his call and getting help). So he got angry that Taemin chose death over life, that and the cocktail of fear, and other emotions (plus plot) that he said "Let me hurt myself so that you would owe me something and that way you would stay with me and pick me (as you owe me now because I hurt myself with your hand)." Since Taemin hurt his family and he tried to get revenge and he stayed alive for them, maybe now he would do the same for him.

Like I said, I like this manhwa because it you can see that they both have problems, and those problems where not seen as problems, it isn't until they are described that you notice and suddenly you find out that they don't really know they have them, or how to solve them either. Human feelings in this manhwa are not as straightforward as they seem. (For example, in the beginning, Taemin sees it as penance, but we see it as depression. Yoon sees it as helping Taemin and being entertained, but then we notice that he doesn't really know how to show that he cares or how to carry relationships because if his past with his mother).


Sorry for the long TEDtalk

Okay wow thanks for clarifying! It indeed surprised me cuz based on the previous chapters I didn’t think he’d to smth like that.

I know, to me, their feelings suddenly became more volatile, and it was out of nowhere. He never treated him that way before, that's why I was thinking No sex.
But then I remember how everyone said that if Jay didn't like something, he would explode and be aggressive, so it was there from the beginning. He just didn't show it in front of Taemin.