ALSO I feel like the second side story is completely ooc. Hyungjae was a terrible person, but everything he did was with one clear goal—to own Jung-Hoon. And now he does. So why is he keeping him drugged up like that? I get it could maybe be said he's trying to keep Jung-Hoon codependent so he never leaves, but I mean . . . look at him. Hyungjae doesn't need to be doing all that anymore lmao
He was actually drugged up often in the main story, especially when he was locked in that room and then another time when he tried to flee towards this end soooo not only do we have all the other stuff you mentioned but getting him addicted on drugs can be added, like a cute little cherry on this shit cake of a story

I get this is a mind break story so I won't act outraged or anything like some other people here, this is a very specific trope, a very specific genre, so I knew what I was getting into . . . But come on, Hyungjae keeping him hooked on drugs like that? Don't get me wrong this story portrays a really toxic relationship, and it's not even particularly a good story either tbh, but I felt like the story ended with them on a relatively high note. That second side story tho just completely ruined that. That first side story already showed Jung-Hoon being mind broken without the inclusion of drugs so why do that Idk I guess it's just in ick of mine. Had this delusional hope they'd fall into a relatively stable routine and dynamic lmao