I definitely do think that the sexual aspect made him pursue Sooyoung but most likely just because he thought he was interesting and wanted to monopolize that in the form of sex. As of right now, from my perspective at least, I think the idea of “conquering” Sooyoung is the main aspect. Making Sooyoung fall for him is the easiest way for this which is all the sweet things he does. Not saying he doesn’t care for Sooyoung at all, because he certainly does in his own way, but he very clearly has sociopathic tendencies and doesn’t feel guilt. Sooyoung just attracts all kinds of people Gyujin the narcissist and now a sociopath. Poor guy lol
I guess as long as sooyoung does what he wants, he won't lock him up at least. I think he doesn't like seeing sooyoung with wounds too, no? I really really hope he's the obsessed but will treat you like you're fragile type ( ̄へ ̄)