#1
Wait and See by oncethrown
After the apocalypse doesn't happen, Dean goes back to Bobby's house alone. He burned Bobby's body in the field. There wasn't enough of Cas left to burn or bury, and Sam was gone. After a few weeks of drinking and researching, Dean's ready to finally off himself and join his whole family, but a discount easter card and a sudden reappearance save him. Eventual Destiel. Human!Cas.
http://www.fanfiction.net/s/8169946/1/Wait-and-See

The Way Back by rainylemons
AU in which Dean gets between Lucifer and Cas, preventing Castiel’s death and eventual return to full-blooded angelhood. In the following months, a mostly human Cas gets a job at Taco Bell, Dean recovers from wounds given to him by Lucifer, and a silent, shell-shocked Sam wanders in from the cold.
http://archiveofourown.org/works/488010


#1 & #5
Return to Sender Address Unknown by Gedry
Castiel falls; becoming human. He’s taken in by Bobby and the Winchester brothers. As his feelings change for Dean he discovers that the path to love isn’t always easy and that sometimes distance really does make the heart grow fonder.
http://gedry.livejournal.com/85645.html


#1
Grace Verse by Enigmaticblue
http://archiveofourown.org/series/9592

Sun Verse by Enigmaticblue
http://archiveofourown.org/series/5064