A mystery keyword searcher is looking for… a short scary story about a ballet teacher who uses her students’ blood to stay young.

Well, it’s not a short story, and it doesn’t have a ballet teacher, but there’s a short YA novel that comes to mind immediately, and that is Dead is the New Black by Marlene Perez. The plot includes a substitute gym teacher and cheerleading coach who sucks away the cheerleaders’ lives to stay young. Maybe that’s what you’re looking for?

If anyone has knowledge of a short story that fits the description above, please leave an answer in the comments. But I’m pretty sure our mystery searcher is looking for Dead is the New Black.