Carmilla

According to the main site, this vampire is going to appear in Chapter 3 of the game.

The main site mentions that she is the right hand and maid of Queen Vampire.

She was in charge of infiltrating with around 30 other high-rank vampires in Sabasa Castle during the Chapter 3 epilogue (demo version), and stays locked in the throneroom after the king discovers her and seals the room along with the whole castle.

She seems to like strong spririt men (like the Sabasa King), but obviously she can't stand a baptized human's blood/semen, and seems to be a bit ignorant about human behaviour (not knowing royal family members are all baptized, something Elizabeth already knew).