
It’s pretty clear that our ML is trying to separate the MC from everyone around him. He’s making him do bad things and the MC is actually thinking it’s right. We always see this reflection in the mirror they always speak about killing and getting back at those who’ve angered you. Our ML has definitely already had this switch, probably the time when their parents died he was tricked into doing the bad things, thinking it was right and would eventually switch over. He’s doing the same thing to our MC. I don’t know if this reflection is a totally different person or it’s just a conscious version of people’s desires but it has control over them. I can’t quite figure out how they killings take place but I think these are the requirements or what would lead up a a killing: the weird sound, a source of reflection, mirror and either someone who posses dangerous thoughts or is the process of switching over. For all that we know that black room might be a gateway. There’s only a mass amount of blood left over when a killing happens but somehow there are body parts in the room. Also, there’s meaning behind smexy time and fear being linked. Looks like a distraction for the ongoing switching
Share whatever thoughts you have

I agree with you. Yeonwoo's main goal seems to "convert" Jun all along. He will join him in this evil practice, but I highly doubt he was innocent in the first place. The thing about the "black room" , it could be the main source of the cursed mirror. We hear noises from that room, we see hands crawling out or going inside it, and we see blood nearby the door. It's also the same room where the the accident about Yeonwoo's parents takes place, though I'm still not sure who exactly killed them, my suspicion is on Jun. It's still a mystery to me how the 'evaporation' occured when both of them are still young at that moment. What are your thoughts?

I like this part where you said, "it’s just a conscious version of people’s desires" because it make sense to me. See, Yeonwoo, as a child, might appear passive and obedient towards his parents who likes to abuse him, yet (maybe), deep down, he held a huge resentment towards them, (or, just anyone in general except Jun). And that is his "dark desire" , which was then manifested by the black mirror into a "persona". This persona might have the ability to "influence" Yeonwoo, seemingly because Yeonwoo himself can relate to it. Hence why, it seems like it can take control over him when it could just mean Yeonwoo choose to submit himself under this evil practice.
Then we have Jun. His "dark desire" might be his obsession of being loved.
He's an orphan, he doesn't know what's parental love is. He doesn't have home or friends that he can really connect with. We also see how he worked so hard to be a role model student too, even in his relationship with others, he's a try hard to please everyone's feeling. The only one who can make him feel special and loved is Yeonwoo. (Excluding his uncle because I think Jun is more infatuated with romantic love)
Back to when they're a child. Once Jun see his precious friend is being harmed, it might have awakened something during that tragedy. Therefore, I think it's him who "initiated" the killing. We also see how Jun is the one who seems composed to talk to the police (chapter 33) after Yeonwoo's parents death, that's highly suspicious. Yeonwoo secured Jun's emotional need, so if he's harmed, Jun would do anything to protect his security. Because when he was young, he was the only one for him, and that might initiate this need to have all his attention, including wanting to protect him from danger.
To put it simply, the truth is, Jun doesn't care about anyone except Yeonwoo. He wants his love and attention, only him can love him that way, and Yeonwoo knows what he wanted. But because of that tragedy, Jun himself felt really guilty and forced a new version of him to get out of that guilt. That's why, once he reunited with Yeonwoo, he's conflicted not about which one is the true him, but what's more important to him. We see Jun's reflection saying things like "Let me tell you the truth", and that truth is really just his dark desire. Yeonwoo's effort to turn Jun towards him, is really just him trying to make Jun submit to his desire because only then he is himself, the Jun Yeonwoo knew, or what the black mirror told Yeonwoo who's Jun really is. The sex we see is part of the plan to awaken his desire. Once Jun turns back, they're together in the black mirror. Now both of their refection are there.

Based on what we’re seeing so far. The ‘evaporation’ takes place whenever our MC is frustrated, confused or stress. Maybe he was the one who accidentally killed the parents under the influence or perhaps that’s when the ML fully ‘converted’ and had full control and the mind set to commit the crime. He was the calmest out of the two after all as he kept his memories when the MC didn’t. Maybe the amnesia is evidence of a failed conversion

It’s pretty clear that our ML is trying to separate the MC from everyone around him. He’s making him do bad things and the MC is actually thinking it’s right. We always see this reflection in the mirror they always speak about killing and getting back at those who’ve angered you. Our ML has definitely already had this switch, probably the time when their parents died he was tricked into doing the bad things, thinking it was right and would eventually switch over. He’s doing the same thing to our MC. I don’t know if this reflection is a totally different person or it’s just a conscious version of people’s desires but it has control over them. I can’t quite figure out how they killings take place but I think these are the requirements or what would lead up a a killing: the weird sound, a source of reflection, mirror and either someone who posses dangerous thoughts or is the process of switching over. For all that we know that black room might be a gateway. There’s only a mass amount of blood left over when a killing happens but somehow there are body parts in the room.
Share whatever thoughts you have

Alright so by now it’s basically been confirmed that our MC has a word ability that surfaces when he’s agitated. Our ML also seems to be trying to control him. Why do I say that? I think that our ML is trying to turn sexy time and pleasure it gives into an addiction. A way so that the MC doesn’t forget about him this time, a way so he doesn’t leave him. I wouldn’t be surprised if this was the case because of previous instances where the ML is basically bribing the MC and using peer pressure.
Next, relating to their ‘abilities.’ I don’t think it’s the MC alone that has this ability but rather the the ML’s own is more controlled. (Only use my the term ability now since nothing else is there to explain the phenomenon. Can’t use mental disabilities when a dude just explodes. It’s something that stretched further.)
Lemme here your thoughts too and also mention anything I missed. I haven’t been keeping up to date recently but I want to figure out the plot before it’s revealed.
Been searching for this for a while and finally found it! I’ve only been reading the novel which hadn’t updated on a while and led to this search #-.-)