Oh I love when other do deep dives, because you're absolutely right. Gyeol is implying what Suyeon is when its really him, hinself and he doesnt even realize it. Also when you said "Gyeol sees Suyeon as only being a sex crazed slut" it comes to play (parallel?) in the last chapter of S2 *SPOILER*
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gyeol looks exactly like suyeon father and his father slut shames his mother and implies it to suyeon at a young age. Gyeol says the sames things suyeon father died about his mother.
When it's really ABOUT* him, himself
oh u keep eating up these interpretations every time...are u an english major
gyeol would constantly use words expressing concern over yoonho and suyeon’s relationship but would never do anything to act from that point of concern, as opposed to the lovers who both feel intensely about every little thing especially with matters involving gyeol. his actions never intensified either, not until suyeon showed the rings he got for him and yoonho.
it was never about yoonho being a replacement for gyeol. it was more so the opposite. because he knows suyeon never cared at all about competition between the two of them as artists, so having suyeon move on from him emotionally is his final straw. however he knew that when suyeon got upset over their past, he still has that chance. so he takes it.
i also noticc how pottery is portrayed in the story. suyeon says something along the lines of liking how through pottery he can manipulate the shape (and basically soul) of something using his hands. then we see that this whole ordeal of suyeon’s sexual preferences started over choking and how that use of hands spiraled into the story yoonho is narrating for his therapist. its a really good parallel and use of theme
random “so” in there ruins it lol why is it there
I was reading the series back recently and we actually learn quite a bit about Gyeol throughout the series it just is very spread out so it's hard to keep track.
In Chapter 19 we see Suyeon and Gyeol in freshmen year and we learn that Suyeon is the top student which Gyeol resents. In senior year we see that Suyeon is still working hard even after finishing his thesis which Gyeol finds annoying. In Chapter 12 Gyeol talks about wanting to help Suyeon and the ceramics department only for Suyeon to remind him that Gyeol was the one desperate to have an exhibit (meaning that Suyeon was having exhibits). It seems like Gyeol was always threatened and by and envious of Suyeon's talent and being the top student.
Chapters 18 and 19 shows Suyeon upset and confessing to Gyeol before he leaves for America. Gyeol agrees to go out with Suyeon after seeing him cry (looks like he enjoys seeing Suyeon suffer). In chapter 38 we see that Gyeol has been ghosting Suyeon telling him he forgot about him. This is where Gyeol tells Suyeon he will only have sex with him if Suyeon can cum from being choked. When Suyeon can't Gyeol tells him that he will only stay if Suyeon can keep him entertained and in chapter 47 we see that Suyeon practiced choking himself so that Gyeol would reward him with sex.
We see in chapter 2 their breakup when Gyeol tell him that he is sick of both Suyeon and his work and in chapter 12 we learn that Gyeol had a girlfriend (probably while he was with Suyeon).
The thing that jumped out the most is how much Gyeol is threatened by Suyeon as an artist. He finds it annoying that Suyeon is always at the pottery wheel and distracts him in chapter 35, when he breaks up with him he makes sure to also mention being sick of his work and he was annoyed that Suyeon is the top student. Suyeon described making his art piece from the exhibit as giving birth to his and Yoonho's child because Yoonho was the inspiration only for Gyeol to say that the piece is funny because it's about Suyeon being obsessed with sex. In an upcoming chapter Yoonho's ex-girlfriend correctly identifies that Yoonho and Suyeon are lovers because their art pieces complement each other but Gyeol sees Suyeon as only being a sex crazed slut.
Suyeon actually spends a lot of the story not wanting to be around Gyeol, being forced to meet with him for university reasons and to share a loft and he calls out Gyeol's bullshit repeatedly. Gyeol was trying to say that Suyeon hasn't changed and that he is still hung up on Gyeol. Gyeol says that he had forgotten about their time together and that Suyeon must be upset about it but it's actually the opposite. When Gyeol realises that Suyeon has moved on with Yoonho, Gyeol is the upset one. He makes a move on Suyeon in chapter 38 out of anger and jealously after seeing Yoonho and Suyeon fuck because he still views Suyeon as his toy telling him in chapter 39 that Yoonho can't replace him. In chaper 47 he says Suyeon being so easy sucked all the fun out of their relationship and in chapter 48 he tells Yoonho he lent Suyeon to him and again says that Yoonho is his replacement. He only wants Suyeon now that Suyeon was moving on but if Suyeon was interested in being with Gyeol he would lose interest again.
TLDR; Gyeol feels inferior to Suyeon as an artist and degrading Suyeon sexually helped him feel better about himself. He doesn't have any real concerns about Suyeon because he went out of his way to cause him as much pain possible with the way he broke up with him and in having a girlfriend.
Suyeon knows this as well but Suyeon is filled with so much self-loathing and feelings of being dirty that he thinks he deserves this treatment and is now stimulated and addicted to it. Suyeon loves Yoonho more than he ever loved Gyeol but Suyeon's is a broken form of love.