Vampire slave

So it turns out I own a vampire slave, minus the thirst for blood. elle has a need to bite Me, hard. Which, unfortunately I can't allow her to do as I'm not big on pain and the biting she gets the urge to do isn't just a sweet little nibble. It's more a, don't-kiss-me-or-bring-any-part-of-your-body-close-to-my-mouth-right-now-because-I-will-chomp-down-and-go-to-town-with-your-flesh! kind of biting. She doesn't know why she gets into this mood, and neither of us can figure out what need this is that she has that is showing in this form. I want to be able to fill this need, but giving My arm to be devoured doesn't seem like the most pleasing or long term solution. Anyone else have this need? What do you do?

Last night she was gently holding my arm in her teeth which I was quite all right with. I tried to encourage her saying it was good pressure, good girl for being gentle, and so on, but I'm sure it was difficult for her to keep it at that level knowing how much, especially lately, she is feeling this need, and I rather doubt that little bit was really doing anything to help her. I'm not sure what to do for My girl in regards to this.