As a person who into BDSM I can say they did they are doing BDSM doesn't have to be sexual BDSM is all about power it doesn't take a scientist to tell there is a big power imbalance between them sooyoung can't even think about his own choices without thinking about taesung, they deadass have a whole ass petplay going on it doesn't have to be sexual to see that he deadass calling him a dog, and for the sexual part they did impact play and even piss play
They are both calling each other dog in a teasing manner. Impact play? You mean that vanilla af spanking in the car? Piss play? Oh sure.
Power imbalance? Lol, no one is denying that. No need for a scientist. Plus it's soooo clear that Sooyung can influence Taesung, even more so than the other people around him. The only thing is that Sooyung is not that type of person that does it but he can greatly influence Taesung if he wanted to.
I said I'm not into BDSM, doesn't mean I don't know what it is nor I haven't read any work that has it nor that I am incapable of doing it. If they are truly doing BDSM then I can say, with absolutely certainty that in terms of BDSM level, this is one of the most vanilla shit I've ever seen.

[Oh wow, blocking me so I can't reply huh? Wow okay XD]
Sure, you do you boo. But I would say that they are not in fact equally fucked up. I'm basically just siding with the lesser of two evil and it's not hard to see which is less evil (especially with the upcoming chapter).
As for the overstimulation, it's Sooyung that should have a say about it.
Isn't victim syndrome where someone uses their status as a victim to take advantage of other poeple? I don't see Sooyung doing that.
Sooyung doesn't have low standards, if he did then he wouldn't have left his ex. The reason why he left his ex is because his ex became suddenly physically violent with him. His ex treated him well for the most part in their relationship. It was only in the later part in their relationship that his ex suddenly changed in personality and treatment of him. That's why when his ex hit him, Sooyung was so shocked because he has never been hit by his ex before and he didn't think he would actually ever get hit by him in the first place.
Taesung is definitely not perfect but he has done good things and that are out of genuine affection and I can't just ignore that.
Plus, that choking thing, didn't both Sooyung and Taesung talk about it afterwards with Taesung even apologizing? It wasn't even a kink or a fetish if I recall correctly, it was just out of anger. So far in the series, they really haven't done any BDSM stuff, it was all just rough sex so I don't see the need for a safe word when they don't do any extreme kinks that would necessitate it in the first place. (That cigarette burning? Now that's BDSM that needs discussing with)
(Also, I would like to say that I have no inclination for BDSM. I don't see the appeal of that stuff)