
It wasn't chemistry, he was just more receptive because he never experienced the trauma of being sexually assualted in the parallel universe.
That shit changes people and the author showed it quite well too. In the main side story, Kyujin has to ask "do you want me to fuck you harder" and Chiwoo couldn't answer even if that's what he wants. Kyujin is gentle with Chiwoo, he respects his boundaries, and knows what Chiwoo likes. That's the kind of love Chiwoo needs.
But in the side stories, Chiwoo asks that guy to fuck him harder because he has not SA trauma. It's seems more "passionate" red flag lovin people, ig.
dude if jihyun wasn't a rapist and violent ugh. I feel like in the smut scenes chiwoo had sm more chemistry w him than kyujin (in my opinion) However, I'm really glad for the ending, bc a lot of webtoons normalize rape and abusive relationships.