Livid's manga / #Brother complex(2)

MC gets unexpectedly dumped by his self obsorbed toxic bf whom he had been dating for many years on a supposed to have been baecation. His exes little brother had always been disturbingly obsessed with his older brother to the point where he would mimic his injuries, which caused his older brother to put distance between them as adults. So when the MC tells him the lie that he actually broke up with ex, the ML/ younger brother can't help but become obsessively curious as to how his idealic brother lost something.