Well, not to disparage the Hegelian master/slave dialectic, but I think relationships are a bit more nuanced. Bear in mind, while the twins put you in charge, you start out with very little to be in charge of, and you are going to have to negotiate and forge alliances of mutual gain. Plus, the other people in the castle see themselves as working for the twins, not you, so you are also on equal footing with them. You will also meet characters who are attracted to you, and if you are attracted to them, the sex will be more about pleasure than a power struggle.
So, long story short, there will be all sorts of sexual encounters.