Since I have taken to writing thousands and thousands of words that will probably not get posted anytime soon (if ever...) I've decided to recommend a story from time to time, whenever I stumble upon a good one.
Steps Behind by Mirrordance
Summary: 56 seals down, 10 left to open. It's 2009, and Lucifer's standing on the welcome mat. At the eve of the final battle in a losing war, the Winchesters make their last goodbyes, and at this end of days, Dean is finally learning to let Sam go.
Now, I suggest you read Mirrordance's note because she has some warning about the story - basically, as she says, it is a tragedy. It doesn't end very well but it's beautiful. Personally, I love bittersweet and even downright bad endings - if you don't, then it's probably not for you. On the other hand, if you don't mind hurting a little then you will probably love it.
It's one of the first stories I've ever read when I started watching Supernatural some time ago and it stuck with me. I read it again a few days ago and it's still as good as it was when I read it for the first time.
Now, get reading! :)