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He breaks his arm I think, or in the process of forcing himself on him, Jun gets hurt. He bites his shoulder . He starts ignoring him at school, and borderline bully him. He sets the stage for him to become a loser. They made up in the novel rn tho. But their relationship is weird. Also, there's a nice guy (allegedly), and Jun wants to fall for him , "use" and then "discard" him.
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The convo goes likes this . Jun: Yohan u gay tf? Yohan: NO WTF. But YOU are . YOU LIKE HANWOO(or whatever that dude s name was). Jun: NO. I was just admiring him cuz he was at the top. Yohan: okay then. I never liked you either. It was just admiration. And Yohan starts treating him badly at school bcs of the night he hurt Jun, they were at yohan s house,he told him "if you leave it's over". And Jun left.
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I don't know much, I didn't read whole novel, mostly only parts about Taesan, but I know Yohan will start bully Jun. Jun will say something what Yohan didn't like, and after that their relationship will get worse. He won't be like Junwoo - Junwoo bullied Taesan openly and hit him himself, while Yohan will do it secretly, to say other classmates to bully Jun. Jun won't know Yohan behind this at first, and Jun will deny he's getting bullied because he will be afraid to be bullied. And Jun will start to compare his situation with Taesan's situation.
Taesan will help to him to understand Jun getting bullied, and will tell it's Yohan. Jun will be in a shock and he will refuse to believe Yohan behind it at the beginning. Taesan will say to him "don't repeat my mistake", and Jun will start to work to stop bullying because he will get afraid he will be bullied at Taesan's level bullying. I don't know what happens next, I know only his bullying won't be at the same bad level as Taesan's - after it's over, on the last meeting with Taesan Jun will think "I had a bad situation, but Taesan's situation was much worse".
I know Jun was beaten at least once, but I think he won't be beaten constantly.
Im only here for Yohan tbh