Stargate Atlantis and Supernatural Crossover

I read this story before and I would like to read it again. What I remember about the plot are too few, what I remember was in apocalypse times. Dean and Cas were sitting around a fire, they were telling John and Rodney that Cas is with him and he is not sharing. They rescued some women and girls from a camp of men.

That is all I remember. I don't remember how the story started or how its ends. I hope someone remembers and how I could find.

Thank you.