Fic: Share Each Other Like An Island [Sam/Dean/Cas]

Title: Share Each Other Like An Island
Betas: I had an awesome group beta consisting of autumn_lilacs, clwright2, gabby_silang, jaimeykay, moragmacpherson, kalliel, switchbladesis, and twoskeletons. And of course huge huge thanks to callowyn for staying up all hours with me and editing this monster. :D I never would have gotten anywhere without her!
Pairings/Characters: Sam/Dean/Cas, with a little Bobby and Crowley
Wordcount: 30,000
Warnings: SPOILERS FOR EVERYTHING UP TO 6.11. Vague mentions of past Alistair/Dean noncon in Hell (nothing graphic), plenty of swearing, and some porn. Incest, of course. NSFW!
Summary: Dean never expected to see his amulet again, much less with Sam's soul inside. But after a century in Hell, Sam's soul is broken so badly that Castiel says it'll take a lifetime to heal, and that's a lifetime they don't have, not with Sam's body still hellbent on killing Bobby. Together, Dean and Castiel set themselves the task of learning the amulet's complicated history, and just what Sam did on his last night on earth.
Notes: This is AU for 6.10 and 6.11. The events of "Caged Heat" never happened; Crowley didn't die and so Dean didn't contact Death as an alternative. Sam did ask Balthazar about a way to keep a soul out and attempt to go through with killing Bobby, but Dean got to him at the last second as he did in canon. This takes place shortly after that. (The title comes from Set the Fire to the Third Bar by Snow Patrol which you can listen to/loop here if you are so inclined.)

Part I | Part II | Part III

The links go to my journal. Thank you!