Not sure if this is 100% what you want, but this continues season 5 in the vein that it was started in. I.E. that the righteous man who starts it is the only one who can end it: http://otp-destiel.livejournal.com/571.html
It picks up all the loose threads that were dropped when they altered the ending of season 5 to make season 6 possible. Like how Dean killed an angel when only another angel is supposed to be able to do that. How and why he was able to kill the Whore of Babylon and all of that stuff.

I don't really know about any gen fics but for Destiel I highly recomend checking the tags on destielfanfic (http://destielfanfic.com/tags) Maybe you find something there, and if not you could always ask them. They have a broader knowledge of destiel fics. Sorry I couldn't be of more help, I swear I know of a fic that fits your criteria but I can't find it.

thanks! I've never come across this site

I'm not sure, but this might fit what you were looking for. It's the second part of what appears to be an ongoing story arc. The first part deals with Dean going to Lisa's after Sam jumps, and the story so far is leaving Sam in Hell. The first story arc is Adventures in Babysitting (Apple Pie Life) http://archiveofourown.org/series/36906. Samandriel makes an appearance in the last story of that arc. The second story arc deals with Dean and how he deals with various angels in the different stories. This is Dean Winchester, Patron Saint (Apple Pie Life) http://archiveofourown.org/series/147576.

The summary for the first story in this arc is: He did not sign up for derailing angelic mental breakdowns. It is so not in his job description…