After tiring of Twilight's hostile attitude, Discord decides to "help" the Elements of Harmony by bringing in an alternate version of each of them. These duplicates from various worlds aren't told anything about each other, which is good. The last thing Equestria needs is these monsters working together.
***Not too dark!***
Elements of Disharmony
Pinkie Pie from Cupcakes by Sergeant Sprinkles
Rainbow Dash from Rainbow Factory by AuroraDawn
Rarity from The Secret Life of Rarity by BronyWriter
Fluttershy from Pattycakes by Pegacorn Ondacob
Twilight Sparkle from Death Note: Equestria by Nonagon
Applejack from Bad Apples by... Bisque? It's hard to find an evil Applejack story.