With the early escape of Nightmare Moon, things in Equestria take a sudden turn. Especially when she creates a virus amongst the pegasi. This event changes the lives of the mane 6 in ways unforeseen by Celestia as they struggle to solve this mystery.
Rainbow Dash becomes a master magic-eating vampire, forms her pack, and works on managing magic with her new role. Friends help out of course. It's actually kinda awesome, all things considered.
Twilight's smart enough to have nothing to do with Rarity and her gang of delinquents. But as her world view is challenged and as Rarity takes interest in her, slowly Twilight finds herself getting closer to Rarity and becoming a delinquent herself.
Twilight Sparkle finds herself being led to question things she's never questioned and try things she'd never tried by Rarity. But slowly Twilight begins to feel like she's being corrupted, and begins to wonder if Rarity is a vampire.
Rainbow Dash was enjoying her new unlife. Partying all night, doing whatever, whenever she wanted. Her new gang, the blood pact, were more then happy to indulge the mare's lust for violence and mares until she gets a letter, delivered by Fluttershy.
The Elements of Harmony are dead. Equestria is in mourning. And yet, while the daytime has grown increasingly darker, the night has become as lively as ever.
In the dark forests of Tramplevania dwells a coven of vampires, their leader being a deadly draconequus named Discord. For many years, his only interests have been in his own survival, until he stumbles upon a beautiful mare with a pure heart.
Equestria finds itself under attack and grossly unprepared for a new and ruthless threat. Fortunately, a certain wizard was pulled into the fight as well, and must lend his knowledge to Equestria and its protectors to help combat this threat.