He will be involved in the story for quite a bit now. Upcoming chapter is about his mother.
Well, we've known she's a lecher and she doesn't care for Valiere at all. This chapter is just showing how they are with each other in private. Astarte is kind of an asshole to everyone throughout the story. Her poor treatment of others comes from her position (Duke), her military successes, and her personal ability (meaning she is a highly capable individual, likely superhuman). She kind of thinks she can do no wrong.
Astarte and Valiere are cousins, I believe. Anastasia is Valiere's older sister.