Your favorite guy, Dipper the Pines, is an evil villain! Wait what?

Sorry for the long title. Now I probably won't be able to update this often so it's just a longer one-shot. Don't expect this too much. Rated E for everyone 11/12ish years old and up. After an incident involving an unknown man named Flan, Dipper Pines, your favorite guy in the whole wide world, turns evil and now the gang, along with Bill Cipher and Dipper's parents must fix him!