What? Seowoo has liked Ohn since the beginning and its cute how he likes all sides of Ohn and not just his "nice side". Jaewoo paid Ohn no attention in the beginning, he never cared for Ohn until this whole favor thing. Seowoo has loved Ohn since the beginning and he really opens up Ohn's soft spots inside. Ohn started being nicer to "Seowoo" because the real Seowoo opened up to Ohn about bullying because Ohn went through it too. Ohn wouldnt be this comfortable if it wasnt for the real Seowoo.. Idk why u say that about Seowoo.. hes just shy but wait until you see him be more brave.. but even his shy side made Ohn feel this way about him. Also Im not giving Jaewoo any pitty when he treats Seowoo like shit, childhood is no excuse to treat your older twin like like this
Seowoo is only INFATUATED with Ohn, he doesn't like him because he knows Ohn and his "nice/bad sides", he likes him just because Ohn went through the same as him and he feel kind of attracted to him just because Ohn could do what Seowoo couldn't do (regarding the bulling). and Yes! Jaewoo didn't like him at first but as a NORMAL person, he met Ohn and started to know him and THEN started to like him, not like Seowooo who doesn't have the guts to talk to him. You say that Ohn started to being nicer thanks to the real Seowoo, but if Jaewoo didn't approach him, the real Seowoo wouldn't have had even the opportunity to say "Hi" and in the chapter where they were in the library you can see that Ohn say he feels flustered when he's with Jaewoo and calm when he's with the real Seowoo, which means he feel more attracted in a romantic way to Jaewoo and in a friendly way to Seowoo... and sorry but what do you mean by "it's not excuse to treat you older twin like this?" because the only thing I have seen in the flashback was the younger brother (Jaewoo) behaving like the older one because the real older brother didn't do it, besides from being "neglected" from their parentes because Seowoo was always sick or whining... As a younger brother he has been only doing his best to make Seowoo stronger. ( ̄へ ̄)
(don't get me wrong, I like Seowoo, but I'm in Jaewoo's side (๑•ㅂ•)و✧)

Why are you all disappointed in Jaewoo? we all knew this was gonna happen.
Nevertheless of the situation, I still prefer Jaewoo, he is the only one who truly knows and really likes Ohn for what he is! And not for a fuc*ing cliché situation like happened with Seowoo. Seowoo has NEVER talked to Ohn, he is in love with his own idea of Ohn! He likes the "cool" Ohn he saw beating some guys and the Ohn in the book, but not the real, shy, cute and very loyal Ohn we all have got to know thanks to Jaewoo! ヽ(`Д´)ノ Jaewoo only made Seowoo a favor by putting al this act. Yes, he could have refused, but (as we have seen) Jaewoo is so used to do things instead of his brother that he never thought something like this was gonna happen. Come on! Get in Jaewoo shoes too! After he did all the job pursuing Ohn, NOW Seowoo wants to take all the credits by telling him to get lost ??
(╯°Д °)╯╧╧
Ok, I'm done ahahah