Ever wondered about that just a little bit? With the current image of a vamp as male, handsome & really quite interested in women of the age when they have this little leak thing going on every month?
I love "True Blood" the HBO series, although I choose not to have a TV, so I wait for the DVD release to watch. The books, by Charlaine Harris, are also v. entertaining, and different than the series. You can read ahead and not worry about knowing everything; the series makes massive changes.
I doubt that even HBO takes on vampires & period blood. However, Harris might just give a little hint in one of the books, Definitely Dead: in this scene, Sookie, the heroine, and her vampire boyfriend Bill have broken up. Bill has brought a date into the bar where Sookie works as a waitress.
"We do something wrong, Sook?" Catfish said. "Or is it just your time of the month?"
"You didn't do anything," I said. And it wasn't my time of the month--oh. Yes, it was. I'd had the warning with the ache in my back, the heaviness in my stomach, and my swollen fingers. My little friend had come to visit, and I felt the sensation even as I realized what was contributing to my general irritation.
I glanced over at Bill and caught him staring at me, his nostrils flaring. He could smell the blood. A wave of acute embarrassment rolled over me, turning my face red. For a second, I glimpsed naked hunger on his face, and then he wiped his features clean of all expression.
If he wasn't weeping with unrequited love on my doorstep, at least he was suffering a little. A tiny pleased smile was on my lips when I glimpsed myself in the mirror behind the bar.
So, Harris is certainly not overtly saying hey vampires will just lick up your menstrual blood as it oozes out, but I think this passage is suggestive.
Here we tasty human women are, with this extra blood coming up every month...if we're not pregnant, we're not doing anything with it...er, unless we are possibly making notorious potions. Or putting out fires. Or enhancing our contraception. Hey! No, vampire, you MAY not have that!