
Hi, sorry for the wait, I just finished the novel.
Yes, he is EXTREMELY good by the end.
Many things happen, the ML had a VERY VERY VERY traumatic childhood, and MC has been his only light ever since they first met
He really has no eyes for anyone else but MC, and, while he still does some questionable things (he does lock up MC), it's very understandable lol. Also, he NEVER hits MC. All the time MC was locked up (a short time), ML gave him literally everything he was asked.
Now, BIG SPOILER UP AHEAD
So, by the end, MC does understand that Sunghyuk is nothing like the novel, and falls deeply for him. Also, and this was not my favorite, MC awakens as an omega (I really like AlphaxBeta).
The end is really sweet, but focus a lot o them. Kim Jun, unfortunately, doesn't appear much. He was very clearly in love with MC, but there's no closure to his storyline.
Overall, I liked it a lot.
I'll leave the link for the Korean complet novel, but the Google translation is meh
https://booktoki468.com/novel/1778043?stx=%EA%B7%B8+%EA%B0%80%EC%9D%B4%EB%93%9C%EA%B0%80+%EC%A7%91%EC%B0%A9%EA%B4%91%EA%B3%B5%EC%9D%98+%ED%92%88%EC%97%90%EC%84%9C+%EB%B2%97%EC%96%B4%EB%82%98&sst=as_update&sod=desc&book=%EC%99%84%EA%B2%B0%EC%86%8C%EC%84%A4
The translation is not yet completed, and it's not perfect, but much easier to read.
https://lilyonthevalley.com/story/how-the-guide-escapes-the-obsessive-lover/

I'm sorry, can I ask you a question about the spoiler, so I usually dislike transmigration but that doesn't mean I wouldn't give chance to read, just kinda icky. So I have a bit of question about this. I only read until 5 chapters though
1. It said he's transmigrated to a BL story so does he have original life before transmigrating? Or he's actually the sub bottom in the story but got reincarnated to the normal world then transmigrated again to esper world?
2. So seme never like Jun? Or what? So what's jun for him?
3. So as you said "seme isn't like in novel" then is what the mc read then? fake bl novel? or some kind of manipulation or something? This is kinda ick me because the seme is so passionate for jun to the point the cover is jun and he locked jun up and have sex constantly for the entire volume lol
4. Seme already like the sub bottom (mc) before jun then?
5. So what's the point of the original novel then lol

Heyo
So, there's is the ORIGINAL novel, and the novel MC (Yeonsoo/Brown Haired uke) transmigrated. The story he transmigrated to is the same novel, but he changes the poly with his actions.
1. He does have a life before, he was an editor for novels, the original novel being one of them.
2. In the original he was obsessed with Jun, I don't know if I would call it love. The ML (seme) of this instance doesn't love Jun, and has no recollection of the original history. He only likes Yeonsoo now.
3. The original seme that Yeonsoo (Brown haired uke) describes and believe to be the real him is the MC from the novel he read, and is very different from de MC of the story he is in now, since his (uke) actions changed him.
4. Yes! He ONLY love MC
5. the point of the original is to set the tone. MC is living in the world of that story, and he knows how the characters SHOULD be like. So that's why he thinks ML is a womanizer etc. But, as he (MC) interfered with the original plot, the characters have changed.
For instance, the seme only likes him, and doesn't ever care about Jun, as he should if the plot wasn't messed up.
So, there's ML, Jun (original bottom), and the MC (second bottom).
In the novel, ML and Jun.
In this story where Yeonsoo was transmigrated and changed things, it's ML and MC, Jun is more like a side character.
If it was not clear, or you wanna know more, ask away.
Sorry for the English, not my language lol
Is this red flag