LFS 'verse Sam/Demon!Dean(?)

[kink_me_quick]

I'm looking for a specific 'verse (or at least one fic and a sequel) where Sam drinks Dean's blood when he needs a fix. I *think* Dean my have been a demon, I'm not 100% sure. I remember Dean being tied to a chair and Sam drinking from him at one point, then I think Dean went along with it because they both got off on it.

I hope that's enough to go on! :/

Thanks!