Massive SPOILER(just a tiny bit)
I wouldn't say Seongmin is a perv, he was just fapping in the office room to relieve 'stress', and also, after reading ch 87,88 i dont think the character Seongmin is really that hard to figure out. He doesn't give a fuck about Yuwon, that's for sure; he just goes with the flow because Yuwon is his senior, and it's rare for a senior to be close to a junior, especially in company settings. Since Yuwon thinks of him as a friend, he lets him think that and acts around it. Before I spoil ch88, i will give a gist of ch 87 first- it started with Yuwon saying that even though he loves Duhoon, he cant breath around him. That he thinks of Seongmin as a friend who really cares for him (he doesnt). That Seongmin is the only one who makes him happy- which takes DH to call SM over to the terrace to talk about smg. They talk it over (about smoking stuff; how it relieves stress and all), it starts friendly, as DH asks how long Seongmin worked and if he and yw were close since then- that if he really considered yw as a close friend like yw did. to which sm said "Of course I do". But DH cut him off with "i doubt that's true"- sm laughs it off- asking what dh meant by it- dh asked sm to drop his act. sm laughed it off again and did drop his act- and said "If Mr Jeong wants me to be his friend if he really wants to think that, how could I refuse that, after all he is senior. i must obey him. and since you and the assistant manager seem so close since way back that, after all. The fact that he became so comfortable around you while you weren't by his side means he changed. things have change", dh cut him off saying, "No. Nothing has changed. especially not jung yuwon. he is still the same. still i dont know why he relies on you more than me. Why he still seeks you even when I am by his side- why he cried his eyes out- saying, only you make him happy. So- Mr Kim, all I want to ask of you is to stay by his side. Make him happy, just like you are doing now. i want you to do the one thing i cant. when when i try to. All you have to do is make sure yw isnt unhappy as he is with me." to which sm asked "since you are being so honest with me, i thought you didnt like me, team leader" dh paused for a moment asking how should he do it- he could make yw happy, he already gave him money and house (smg yw wanted when he was in hs not now)- so which sm rejects his offer- saying he cant do- that making sm happy geniuenly in difficult- and that one wrong move and he and yw might fall for each other- and he askes if dh was still okay with it to which dh laughs and says 'haha, mr kim you dont need to overthink it- all you need to do is continue what you have been doing till now. make yw happy." sm still rejects him offers and calls out saying "you want to know how to make yw happy, right.? " with it ch 87 ends. and with ch 88, continues - DH pauses not sure what made sm change his mind but sm continues saying "because i feel bad for him. if you want to make him happy. ask him one more time. what he really wantes, not what he wanted back in hs- but what he wants now. because i m pretty sure its different now, bcz people change- even without realizing people do change. he too has changed. so please, ask him one more time what he really wants" back at home, dh and yw were choking each other when dh asked what yw wanted- to which yw said he wanted him to choke harder- fuck harder- DH knew yw wasnt happy- he knew it- but he delusioned himself into thinking that -when yw smiles as he loses his sanity- DH was making him happy- he didnt care about yuwon happiness anymore- he was fulfilled by that suffocating laugh- he didnt need sm to make yw happy anymore- only he was allowed to do that- yuwon only needs him and no one else- with that two week passed- and went out to visit sm to was busy fapping with a hammer, to which sm humored "what is it, team leader? need more relationship advice?" now- he will turn into a flowerpot.

mf does end up in a flowerpot. Such a waste of aura.