HELP

thats his step brother but people are saying he's his cousin who became his step brother. his names jaewon i think, me personally i think jaewon did that to tease mc. originally i thought jaewon blackmailed or forced himself onto seoin but someone pointed out that seoin looked like he was enjoying it (ch2) so im just hoping jaewon said something like "pretend im youngwoon and kiss me" but thats just weird ngl. in the last few panels of ch31 it looks like jaewon was bullying youngwoon (their moles are opposite from eachother if u get me) and when seoin was leaving the country, he was waiting for youngwoon at the airport with his mom but his mom said he wasnt gonna come so i think jaewon came instead, thats why jaewon said "i just came from the airport and my hands are cold" or something to taunt mc

So: ML had a brother named Jaewon, who is not blood related to him. The bro is dead today.

Back in highschool, ML had black hair and his bro light one. MC and ML hanged out, and bro sometimes tagged along. As MC and ML started falling in love, MC saw ML kiss someone else (we don’t know who) in classroom.
MC broke his friendship with ML, as to not get his feelings hurt more. Both experience heart break.

BUT, as we can see on « close up » in ch20 and 21, is that when he his kissing random guy, ML doesn’t have the right moles.
ML has a mole under his right eye and under his lips on the left side. Bro has only one mole, under his lips on the right side.
On the kissing picture, ML has black hair, but no mole under his eye, and a mole under his lips on the right side.

ML leaves the country. Bro starts bullying MC. MC experience something traumatic (we don’t know exactly what). MC experience abuse at home (from what his debtor friend hyung suggests) and runs away from home. ML is even more heartbroken that MC left.

Years pass, brother dies. Probably from health problem since doctor from spiking incident chapter (around ch6 I think) said they used to be the bro’s personal doctor.

We understand from ch7 or 8-9 that ML and his brother didn’t get along (probably after highschool? Since they hung out together with MC.)
So bro probably hated ML for being gay/because jealous/because not entirely related, and took it out on MC to ruin ML’s relationships. Or he had some twisted crush on ML and so despised MC

Ok, that was VERY elucidating!! Thank you!!!

OH OK!!! Now I get it!! Thank you so much! You both helped me a lot! I thought that the kiss scene was seo in, but now everything makes sense