James is right about the light from the other room... and being able to see the other room really wrecks the effect of the girl in the candlelit room.
IMO, the first and second shots would work better in B&W. B&W strips an image to its essentials. The color tends to sap the tension out of the pictures.
But the third shot doesn't work for me on so many levels. First, that image superimposed on the background is a big distraction; the posterized face graphic is too harsh, too obvious; a layer of straight photo of the vamp's face with heavy backlighting and with a low opacity might work. And the vampire is armed with a kitchen knife? Why? She has fangs to draw blood. If she wants internal organs for a meatier snack, she has claws and an inhuman strength with which to open the chest cavity.

A knife just doesn't make sense in the vampire mythos. The image also doesn't take enough advantage of shadow and light. The light is too evenly distributed around the set... or at least the bed. Consider a 10-degree gridspot on the victim's face and breasts and some underlighting on the vamp's face and backlighting on the rest of her. Check out some of the scenes in the old 1930s horror movies.
It's a fine start for working with multiple models and a complex theme.
I actually like that second image on its own merits. I like it a lot.