(incoming spoilers)
basically, juyeon really tortured jiwook each time he "misbehaves" (it gets worse each time) then one day while juyeon went out to visit his mother, jiwook tried to escape with the "help" of suhyeok and ofc it goes all bad; this is also where juyeon unravels and gives us a backstory as to why he's even doing this to jiwook. apparently they met when juyeon was a middle schooler and developed feelings for jiwook but jiwook did not take that well and was homophobic, then one day jiwook and his group decided to gangr*** the 14 yr old juyeon, and jiwook doesn't remember that at all. so after the failed escape, juyeon brings both suhyeok and jiwook to a sketchy torture warehouse and reveals what happened that time to suhyeok who was bound, and juyeon also gathered different people/thugs that jiwook fought before and made them do what jiwook did to juyeon before. so after that, juyeon brings jiwook to the hospital and jiwook vaguely remembers what he did to juyeon, and while they talk jiwook reveals that he DID like juyeon but has internalized homophobia (jesus christ) and jiwook has been successfully made super dependent on juyeon so boogsh they still end up and live together (jiwook still assumably on a leash and forbidden to interact with the outside world)

yeah, i guess they belong with each other jesus christ