[quote=@Wraithblade6]
[@Witch Cat] eh... changing the dna of every single cell in a body is a bit complicated. Every cell has to change EXACTLY the same, at the same sequence, same code, etc. I think we should go with disease. If you want to explain thralls, make it so that the body has to physically die, or maybe consume a certain amount of vampire blood, or get infected a certain number of times in order to go full vampire.
[/quote]

Yes, but like, vampirism is tainted with magic. It all did stem from a powerful demon. Magic can do alot of things, transfiguration is one of them. So, I don't think it's outlandish to say vampire blood can transform every cell. And who knows? There can be hiccups that lead to mutations! Room for more tweaking!