They have the hots for each other. But ones in denial, ran away from home. Joined a gang. Became gang director. His step brother ended up working as a detective/cop who were trying to bust their gang/operations. The boss (dude with green hair who used to be blond and fine who's now obese) found out his step bro is a cop so he set them up to take them both out. But luckily he didn't succeed. And the gangster brother fell off the bridge and presumed dead. So in order for his gang brother not to go to jail the cop brother holed him up and just comes and bangs him whenever he wants. If both of them are known to affiliate with each other and the cop brother doesn't take him in then they would both be in jail. The boss in the past made a move on the gang brother but stopped when he realized that guy was calling out JeeHan's name.
Thank you for explaining
Idk what happened at all but oh well