Pre-Apocalyptic Future!Fic (I know, that sounds wrong, BUT!!)
On The Shores Of The Great Lake by eliza_jane - Slash, Dean/Cas, future!fic, slightly AU from end of S5, her summary: "The problem with the war between Heaven and Hell is that it’s never actually over. The problem with being one of God’s chosen warriors is that you can always get called back into the fray.
OMG this is AWESOME. It's reincarnated Dean and Sam, who don't know they're reincarnated Dean and Sam, and then Castiel meets them, and Winchestery-ness and Destiel ensue. Basically, Heaven and Hell are having another crack at it, but forgot to ask Dean and Sam if they were ok with that. Also, awesomeness about the whole Winchester Gospel and Edlund Prophesies and hunters being kinda recognised but still kinda in the shadows and and and ZOMG JUST GO READ THIS FIC YOU'LL LOVE IT. It's 11k so pretty decent fic to get lost in without losing whole days, which is good, cos I tend to get so caught up in megafics that I stop being a functioning member of society sometimes! O.O It's really well written, and the introduction of the boys' reincarnations is really interesting and well done, tied in with the introduction of how society is in this future and what everyone believes about everything that happened. I really like the alternate ending of S5 given as to how the apocalypse was stopped and what happened to the boys during and after, and the descriptions of how Castiel's changed over all the time passed, and how he feels about Dean, and the lovely sex scene is adorable and sexy and really very loving, without being at all angsty, so added bonus there, cos so much of the sex in SPN fanfiction is angst-central, so it's nice to have something different.
Basically, I love everything about this fic. It's really really good. Go read it NOW. Go on, off you go!