Ignored's manga / #psychological(13)

Would-be-Seme (not MC) marries uke's sister Was already mutual The uke ends up with a new guy (mc)

An outstanding Minjae secretly falls for his adoptive father Hyukjoon, tries his best to be a dutiful son while sleeps with his close friend, TaeHyun as a replacement. But Hyukjoon isn't proud of Minjae. Hyukjoon's son died years ago. And the one responsible for his death lives with him. Minjae isn't Hyukjoon's son. He's his target

Yoseob, normally very quiet and composed, is in the police station convicted of stabbing 8 civilians with a knife. Does he, a mere high-schooler, have any reason to have done such a horrifying act? Does his obsessive love for his older brother, Jaeha, have something to do with it?