Kvikindi

A rambunctious child, who once ran off to explore a castle, only to get turned by the Lord, who was still experimenting with keeping vampire thralls. It was a death by bite and vampire blood ingestion. The turning process took actual weeks. That's when the Lord decided he was too impatient to turn people this way, and decided to just straight up poison the next people who wandered in. 

Genderless. Unusually good at shapeshifting, but since they were young, almost every other vampire power of theirs comes with major drawbacks. 

Their hair went completely white because of their bat form looking like absolute cotton balls. 

Escaped the castle.... later. After their whole castle group got rid of the Lord, Kvikindi decided to stay at the castle and guard it, looking like an actual dragon. Terrorizing the medieval-time locals was fun for a while. Then they moved on. 

Nobody really knows what they are up to right now. Probably died at some point.