Just like her partner in two initials George R.R. Martin, J.K. Rowling is releasing 12 days of digital Christmas gifts for fans. Today’s Pottermore update: a story on vampires, which Rowling admits she didn’t include in Harry Potter because “there was little I could add to the tradition.” Besides, she says, vampires are an Eastern-European thing, and she tried to draw more from British and Celtic mysticism when creating Harry’s world. Still, one bloodsucker does make a brief appearance in The Half-Blood Prince, and Rowling admits she had plans for another: a vampire teacher named Trocar, who would have presumably only taught night classes. Rowling adds that, despite appearances, Severus Snape was not a vampire either, making this the latest Pottermore update to come back to Snape in the end. We’ve previously learned why he became a Potions teacher and all about the drab industrial town in which he grew up, though Rowling has yet to confirm whether or not Snape was based on Antonin Scalia.