possessed/dead!Sam old story

[itylien]

I'm looking and failing to find the story where Sam dies and his body is being possessed by some kind of unspecified... thing that killed him and recently ate a succubus. He legitimately dies and Dean is left with Sam-shaped shell that uses him for energy. Very sweet, romantic and also very good story that I can't remember title, author or location of.
Also any and all possessed-and/or-gone/death-but-stil-somewhat-Sam stories that can be found. This is very... specific craving that I have troubles putting in searchable terms.