She is a muscled and imposing natural blonde who is about six feet tall, leggy, chesty and slim-waisted, handsome rather than beautiful. She looks like a bodyguard from some bad spy movie. Her eyes are a little too small for Anita's tastes.
Like Janos, who presumably made her, Bettina is a rotting vampire. When she rots, she dries out like a mummy, ending up barely more than a skeleton.
When we first meet Bettina she is wearing black leather and her long, yellow hair is in a braid down her back. She undoes the braid and shakes out the hair into a thick curtain for the sex. The crotch of her leather pants can be opened somehow. Later she's clad in a black dress that leaves her shoulders bare, with a throw of cloth over one shoulder and down the front, secured in place with a tight gold belt. Her braid is wound in a crown atop her head.
Pallas and Bettina guard the two girls Serephina has had brought in for entertainment for Jean-Claude's visit. They are to whip the girls unless Jason and Larry agree to take their places. The boys agree, but Jason's part is changed into having sex with both Pallas and Bettina right there with everyone watching. He hesitates, but goes along with it, and seems to even enjoy himself until they allow their flesh to rot and decompose in the middle of the act.
When the fighting starts Pallas and Bettina abandon Jason and go for Anita instead. Jason drags Bettina off Anita. The next time Anita has time to pay attention to them Jason is tearing into both Pallas and Bettina with his bare hands and scatters bits of them widely around the floor.
Later, when Janos leads a group of vampires to the graveyard Anita and Larry are at, to bring them to Serephina, we learn that Bettina indeed didn't die despite having been ripped to pieces, as the pieces weren't burned afterwards. Anita and Larry are unable to stop Pallas and Bettina from killing Mr. Stirling, but at Anita's request Pallas puts him under for the draining, so he doesn't seem to care when Bettina plays with his broken arm. After Jean-Claude arrives and promises to accept the 'invitation', Pallas, Bettina, and Janos all take into air to make their way back to Serephina.
At the party, the trio stands guard behind Serephina's throne. Serephina has plans to give Jason to Pallas and Bettina, who are supposed to teach him to enjoy rotting flesh. When the fighting starts, Larry keeps firing at Pallas and Bettina, but his silver bullets have little effect. His cross keeps them a little out of reach, though. After Anita wakes up from Xavier's control, she finds that Bettina is one of the vampires who have piled on Jean-Claude to keep him lying down.
When Anita wakes up at the Bloody Bones restaurant, she finds Pallas and Bettina snuggled around Janos on the floor, in their daytime death. Bettina is presumably killed when the building is burned down around her.