I think it's been recommended quite a bit already, but here's my two cents on it. When canon falls short of its potential, fandom steps in: Recall
, Sam/Dean. If you want to see a Sam who is truly disturbed as befits current canon, read this. If you want to see Dean who is scared and sad and still strong, always, when it comes to Sam, read it. You want to hear the character voices, read and recognize some tie-ins to canon, yeah. And with all that, it addresses that horrible, so-wrong voice-mail that may have been the final turning point for Sam - THAT one, the fake one from Dean to Sam. Then add to it Wincest that flows naturally from the story so that it's almost inevitable. I love it.
I'm currently working on Vid Show C - my recommendation series for vids I love:)