I see what you're saying but I beg to differ. It's very clear that Hajoon has done nothing but always want to separate himself from that weirdo... from choosing to go to uni, moving in with Danwoo, having his own friends (his new found freedom is literally what makes Hajeol revert to such sick measures in order to get back Hajoon's attention). I believe the only 3 times he feigned to be Hajoon was when they went to the adult shop, the dinner at the fancy hotel and the unfortunate SA by deception.

Hear me out, I was rereading this and it seems like the twins were working together and switching for, at least, some purposes. When one of the twins mentioned dinner in class, then the older twin went to a fancy restaurant, it looks like the younger twin switched back after the older one left in the car. At first read I thought it was just that the older twin knew of the younger’s schedule, but then the younger twin mentions “we just ate??” Also, how is the older twin making plans through the younger twins phone number? For this in specific I feel like the older twin might have just said he promised a meal and the younger twin of aggreed to let him go. Also, it seems like both of them knew the MC passes out after sex. Idk there just seems to be too any coincedences. I'm not saying the younger twin let everything happen, but I think maybe the older twin took it way too far. Thoughts?