@XoXo
Spoiler!
Yohan was the favored child before his father struck him with a trophy. He was really smart but after he got struck it sort of messed up his head after that started the decline it made it a lot harder for him to learn and he couldn't keep up with his grades,his father of course lost interest in him now that he no longer was good at the one thing he was able to show off and that's kind of when he started to close himself off and become in outcast in his family,this is the main reason yohan had such a strong reaction when jun did that because yohan feels shame in the fact that he no longer can provide his father the one thing he was good at and fears his father so jun embarrassing yohan in front of his father is kind of salt in the wound and made him lash out. Also keep in mind that I believe this info comes from yohans perspective which is shown to be not really reliable if you're interested you should genuinely read the novel it's honestly a really fast read
I fart glitter