Millie Wren--The Winchester's Sister

Millie Wren Winchester, Sam and Dean's sister, two years younger than Dean, two older than Sam. Pissed at her Dad, while Sam is away at college, Millie Wren decides to leave Dean and John to go hunt off on her own. Away from John. She leaves in the middle of the night from one of their crappy motel rooms. "Stole" a car, and took off. That was four months ago. She's been keeping in touch with Dean, and Sam. John can fuck off as far as she's concerned.

What does a third Winchester add to the plot of the story, what does it mean for the story? Let's find out. I'm going to hold as tightly to canon as I can with adding a third (technically fourth) Winchester sibling.

I don't own any of the characters of Supernatural except Millie Wren. The only story lines I own are the ones that Millie's existence causes something to differ from the original plot.

Also. Heads up, this is probably going to be a long book/series/something. This isn't something I'm going to be able to forget about until it's done. So... good luck. And also wish me luck.