I see a lot of confusion, so let me sum up the story : ML and MC used to have a crush on ...

I see a lot of confusion, so let me sum up the story :

ML and MC used to have a crush on each other back in highschool. MC was a promising judoka under his father’s training, and ML was a fan of his. They played around without confessing their feelings. They hang out, sometimes with ML’s step bro (ch10), who is older than ML (ch9).
Step bro has poor health, and so a personal doctor (ch6: said doctor says she used to be. Ch8 she recognize MC, from back he was in highschool. So yeah, step bro had poor health for quite some time).

One day, MC stumble on ML kissing someone else in a classroom (ch2). He breaks his friendship with ML as to not get his feelings even more hurt.
But, something is revealed to us in ch20 and 21. We can see the picture of the kiss better, and something is wrong.
Back in highschool. ML had black hair. He has a mole under his right eye and one under his lips on the left side. His bro has light hair, and only one mole, under his lips on the right side. But on the kissing picture… ML (black hair), has no mole under his right eye, but a mole under his lips on the right side.
ML his really surprised, to say the least, by MC breaking his friendship with him « so arbitrarily. » (ch21). His step bro tells him that people couldn’t « possibly be genuine with him ».

MC had problems at home at the same time. His father was in debt. (Ch26) That’s how he first met his brown haired hyung, Taegu (the debtor one.) Taegu observed that MC’s dad might be abusing MC.

ML leaves the country for three months, and is hurt that MC didn’t come see him off. Step bro bullies MC, and visibly makes him go through huge trauma (ch31). So much is still sometimes take medication 10 years after.

MC ran away from home, and gets help from Taegu (the debt guy, ch27). Taegu acts kind of like MC’s hyung. ML comes back home, and is even more broke hearted learning MC has run away.

Years pass by. ML and step bro don’t get along (say other family member in ch8).

Step bro dies.

10 years pass by. Taegu works now in the entertainment industry at a high position, and got MC a job as a manager. He pays MC a higher rate than his other managers (ch26).
MC’s only contact with his father is paying his debts and hospital bills (ch25.) His father is in poor health.

ML is still a model like when he was a teen. He sleeps around and doesn’t get attached to anyone in particular.

MC meets ML again. ML has held a grudge against him all this years. But he wants him still. So ML hires MC, MC accepts cause he still got lingering feelings. ML abuses MC multiples times on the pretense of broken heart when they were teens. They both are confused thought really attracted to each other.
MC thinks ML just wanna use his body. He wants to protect his feelings but at the same time wants to be near him.
ML doesn’t understand MC. He wants to use his body and hurt him so to not feel anything for him anymore. But at the same time wants him for himself. And he doesn’t understand why MC acts interested in him but places limits « out of nowhere » (from his point of view)

So yeah, communication is key guys.