When she first met Freddy Martinez and Cara Simonetti in Count Nightwing's castle, Gwendolyn claimed to be not be a vampire. She said she was a human that the vampires treat as their slaves, making her clean their coffins. She seemed to know a way for the kids to escape from the castle.
However, it turned out she was a vampire who had just wanted the kids all to herself. Nightwing showed up to fight her and the Freddy and Cara escaped. It is unknown what happened to her after that, as Nightwing focuses on getting the vampire breath back when he catches up to the kids.
In the TV episode, Nightwing turns her into a cockroach, while claiming that she "bugs" him.
She is very manipulative, as she tricked Freddy and Cara into thinking she was one of them and almost had them all to herself.
She has ringlets of blonde curls that flow past her shoulders and pale blue eyes.