I really don't see this going the "love-triangle" route, the brother is pretty clearly made out to be the villain in this dynamic, and even though Ideum and Jaeyi aren't in an official relationship, Ideum hasn't really been presented as the type to think "well i'm unattached and free so i'm gonna go screw jaeyi's BROTHER who's overstepping like crazy, even though that would clearly completely destroy my relationship with jaeyi, even on a friendship basis, ahahaha~~"
I think the brother is just gonna be an annoying hindrance to cause trouble in their relationship in the whole "Why can't you just tell him to screw off?!" and "Well you're the one who said we should just be fuck-buddies so why does it matter so much to you?!" way.
I really don't see this going the "love-triangle" route, the brother is pretty clearly made out to be the villain in this dynamic, and even though Ideum and Jaeyi aren't in an official relationship, Ideum hasn't really been presented as the type to think "well i'm unattached and free so i'm gonna go screw jaeyi's BROTHER who's overstepping like crazy, even though that would clearly completely destroy my relationship with jaeyi, even on a friendship basis, ahahaha~~"
I think the brother is just gonna be an annoying hindrance to cause trouble in their relationship in the whole "Why can't you just tell him to screw off?!" and "Well you're the one who said we should just be fuck-buddies so why does it matter so much to you?!" way.