Back Into The Dark

Caitlin Winchester. She's the oldest Winchester. Or she was. Before she died. At 18 years old she died on a hunting trip with her dad. The boys were in a small town waiting for the two to be back. While hunting a werewolf Caitlin is bit. Not wanting to become a werewolf she begs her dad to kill her. John fufills his daughters last wish. Or at least that's what the boys are told.

Once the boys learn of their sisters death they're broken. They grief on their own while John continues on his quest for revenge for their mother. Little do they know their sister isn't dead. But she isn't the same.

John and Caitlin weren't hunting for a werewolf. They were hunting a Demon. During the hunt the Demon threatens to kill John so Caitlin made a deal. She'll go to hell for her dad. The Demon refuses, saying the only deal he'll make is that Caitlin will be a Demon. Caitlin reluctantly agrees and she leaves with the Demon.

Now it's been years since Caitlin left. Dean only has a year left. Sam is willing to do anything he can do save his brother. That's when he learns of a Demon that has gone rogue. The Demon fights hell, and helps humans. Doing anything to piss off the other Demons, especially Lilith. Sam immediately attempts to find the Demon. And when he does he's shocked a long with Dean.

How will the brothers respond with their new ally? Will this Demon betray them? Or will their hate for Lilith be strong enough to let them fight with these hunters? And where does the oldest Winchester for into all of this?