The ML yearns for the MC, and in his presence, behaves accordingly - he's sociable and polite. However, he's actually indifferent towards, and I'd say annoyed by anyone who isn't his hyung.
The ML is mostly indifferent to others and has a rather serious, unapproachable exterior, but he isn't indifferent to the MC at all. He has his mind set to finding the MC and getting to know him, and no one can stop him.
The ML has a disdain for pretty much anyone who isn't the MC. He's very closed off, harsh and abrasive. To an extent, this is first directed at the MC as well, but changes later on.
MC is an emotionally closed off man wearing a pokerface at best and a serious frown for most of the time, who is also involved in criminal activities. However, he has a very soft spot for his crybaby ML.
The ML has a horrible, violent, dog shit personality, and the MC experiences it at first as well. However, through certain events, this changes abruptly and the ML is obsessed with the MC and pretty much has only eyes for him.
The ML is an introvert who tends to be snarky and rather distant from people, he'd rather stay home or avoid crowds and meetings with people altogether. He doesn't have any friends either. However, he falls for the MC during their rivalry for the MC's high school best friend. He even beats up a piece of shit who tries to blackmail him and put the MC's career future in danger! He also breaks down and cries because he can't get over his feelings for the MC!!
The ML suffers from chronic insomnia and lives isolated from most people. He's rather abrasive and blunt, with not much regard to or interest in other people. That changes when he meets the MC for the first time, although in a situation that initially pushes the ML away. Under weird coincidental circumstances, both become closer and the ML quickly becomes dependent on the MC to help him with his insomnia. He gets very attached to him, clingy even. He cries and is soft only for the MC.
For You Who Grieves