dude, you fucking kill my heart and soul with your smartass thought.
I agree. But this is just my theory:
The Dohyun we know only started to remember Sungho under extreme distress. Right after he was chained to the bed going in and out of consciousness. Shortly after he read Sungho's diary and that is where he gathered the information. Dohyun is desperate to find a way out and is pretty much doing everything he can possibly fooling Sungho into believing he is the real Dohyun.
Now if you are wondering why Dohyun would do this? . . . because he knows Sungho would not kill the real Dohyun. Dohyun would be more likely to survive even if he gets raped. After being tortured for so long by Sungho, Dohyun would start to even believe he is the real Dohyun.
Keep in mind that before being strapped to the bed, Dohyun was convinces this was a random attach and he had no idea who his kidnapper was.
Also it has been 9 years since Sungho last saw his Dohyun and lost all contact, that's why the old man had scouted Dohyun first.
If this is the real Dohyun, he is suffering from Prosopamnesia. In chapter 1, Dohyun mentions that he cannot work delivery because of a near death accident that happened while it was raining. He can't even remember the faces of his mom, aunt and uncle, let alone his high school friends. The fact that he all of a sudden remembers Sungho's face is highly suspect.
I don't think Dohyun has a twin though. If you review his flash backs from childhood, he recalls and aunt, uncle, mother, teacher, classmates and a friend who he owed money to and that's about it. If he remembers his mother, who seems to have abandoned him, he should remember a brother.
I know it's obvious but I just want to point out that Dohyun avoids relationships with people because every important relationship he has ever had are of his family abandoning him and his lover's trying to control him.
Dohyun has learned to live by building walls between him and other people.
Lol, I'm so sorry Σ( ￣□￣||)
OH. Thank you for the explanation (づ￣ ³￣)づ
Just a theory. I could be completely wrong. lolz. (￣ε(#￣)Σ
Observant. I'm having a very strong feeling, even more so now, that Dohyun isn't Sungho's Dohyun, whether it's a doppleganger, a twin, him with amnesia, or even that somehow Sungho's trauma replaced the faceless teen in his memory with Dohyun, someone who reminded him of the real culprit. Idk, but it seems that way.