Saving Faith had a great one (HBO!Verse, Dean/Castiel canon, but also Jensen/Misha RPS), but she's pulled her fics for now (and doesn't want them circulated), so if she ever posts them somewhere again, I highly recommend that one. There's a great scene where they're at a convention and it's from a fan's point of view (presumably the author), where she mentions Jensen to Misha and notices that it throws him a bit. One of my favorite scenes in the fic.

Other than that, I'm not sure if I can help you. Other than a few FP fics where the boys interact with the Supernatural book fans who maybe mention some Dean/Castiel stuff briefly, I don't think there's any out there. But the SPN fic fandom is a vast place, and just when I think I've seen/read everything, people are reccing things I've never heard of.

So hopefully someone else out there knows of something, because I'd love to read that story.

Sorry, this was kind of a teasing comment, and possibly pointless since you can't read Saving Faith's story. I love her work. I hope whatever's going on gets resolved soon.