Not the person you’re replying to but I’ll try to word my perspective on why people (including myself) might be attracted to “irredeemable” villians. For me at least, part of it is exploring potentially dangerous subjects without any personal risk? If that makes sense. Part of the appeal if choicescript games is that you can play pretend.
Like in the case of Manerkol, in real life, the relationship would probably be considered abusive with a dangerous power imbalance, but as fiction, I find it almost thrilling to be able to be involved with a dangerous, domineering older man. Its sort of a forbidden fantasy. With Manerkol there’s also the aspect of him being incredibly wealthy and powerful but since the PC is a sort of reluctant participant it feeds into the fantasy of being taken care of by someone rich and powerful without being labeled as a gold digger.
With Jun/ko I think its more of the traditional reason people are attracted to bad boys? Like its a different sort of “not dating material” but the fact that they’re vulnerable to only the PC with the player being implied to see sides of them no one else ever will because you’re (even in a messed up way) special to them. While some people dislike how Jun/ko treats the PC at in the beginning of book 4 (I think) to me its not really a deal breaker because I don’t really see it as any more problematic than say, watching a particularly spicy adult film.
In both cases, another part of the thrill is that they’re unequivocally obsessed with the PC. While irl, such a thing would be dangerous, its almost a guilty fantasy enjoy reading fiction where your romantic partner is undeniably yours, in Jun/ko’s case, their obsession blinds them to even considering anyone else, in Manerkol’s they’re literally your soulmate. I guess it lets you fantasize about a world where insecurities don’t exist and you never have to worry about not being enough because you’re made for each other?
EDIT: and if it wasn’t obvious, I’m a huge fan of both Jun/ko and Manerkol lol