Applejack is a hardworking pony. That is, until her sister buys a mysterious ingredient to add to her sister's water from a dark salespony. Suddenly, Applejack is farmpony by day, bloodthirsty murderer by night. But she cannot control her urges, being incapable to eat anything but pony blood. Struggling with keeping her secret from Ponyville, Applejack is surprised to find another pony with her secret, her best friend no less! But when Twilight Sparkle and Princess Celestia get involved, will they continue to murder ponies in the night, or will they be punished by the Princess of the Sun, their enemy?
My first story, and I suck at summaries, :(