Nah he's actually not as bad as you think. Iirc from the raws he actually indirectly/secretly helps them with something. But I could be wrong because I was using Google translate to read them
From what I understand from the newest raw chapter, he's trying to do some pest control. Do-jun is too nice and there are ppl want to take advantage of him and the step brother kind of stalks him and warns the one he deemed as bad guy to stay away from Do-jun.
Okay alright, that makes me feel a bit better
*stalking him
The step brother is still obsessive about Do-jun to some degree but the new love interest can change that.
If creepy ass bro took a pic of the main couple to blackmail ML I WILL THROW HANDS
To everyone that is more excited for the second couple/dislikes the main couple YOU’RE SICK