I read this fic somewhere a very long time ago and have been searching for it off and on for some time now, without much success. For the life of me, I can't seem to remember the name of the fic or the author.
All I remember is that it was (most probably) set post season 5, when Sam was still in Hell. Dean wasn't dealing very well with his brother's death. He kept having dreams about Cas drowning and/or dying in a river of some sort, but after what happened to Sam, he just couldn't bring himself to care. Later, Sam returns to Dean with a bleeding Castiel in his arms. It is discovered that and Angel's blood has the power to open the gates of hell and free soul trapped there. Hence, Cas had sacrificed himself to rescue Sam from Hell.
Cas finally dies, leaving Dean broken-hearted. However, Gabriel shows up at the end and tells Dean that moments before his death, Cas tore out his grace and became human. Thus, his soul is now in Heaven and waiting for Dean. He also says that Cas wants Dean to live a full and happy life before his death.
This is all I can remember, unfortunately. So if any of you wonderful SPN-ians know this fic and where to find it, please let me know.
Any other fics with this kind of theme are also very welcome.
Thanks in advance! :)