This is the story of Millicent or Mil Winchester, the younger sister of the famed hunters; Sam and Dean. This follows her story with her brothers on their many hunting expedition. Starts ep 1:01 Pilot and will continue indefinitely

What happens when Dean, and Sam Winchester find out they have a sister who isn't exactly human, and has a lot of secrets

Valerie Scott is in eighth grade. The day she meets the Winchesters something bad happens. Everyday it somehow goes downhill until she's forced to stay with the boys. She goes against her beliefs and becomes a hunter. When she thought any thing couldn't get any worse, it did. That was the day she met Castiel. Castiel tries to prove to Sam and Dean that this harmless 13 year old girl, Valerie, isn't claiming to be who she really is. As the story goes on, the mysteries unfold. Valerie finally finds out who she was. And who her father is.