I'd love to be able to do more with the Nyx Parasites. Maybe infest some of the folks in town or our party members like the imp. Getting more options with the minotaur guard and possibly some parasite play with him would be cool too.
On the note of the minotaur guard. It'd be nice if, when you become his master, you ask him not to stay inside so he doesn't fall to his corruption. That'd also open a route for later inducing it by seducing him and infesting him yourself.
Just some thoughts.