Nah, Jaewoon (dead bro) is the one with the original blonde hair not Seo-in (Seme). They both have moles near their mouth but in opposite sides but Seo-in has an additional one under his right eye while bro doesn't have one..try to check the family photo again, u'll understand what I mean
so who was bro kissing in the beginning? when mc ran away in the school hallway? was it ml brother? I’m so confused I need a backstory