Title: Profoundly Different
Authors: amireal and tiamatv
Summary: "Castiel?" Sam calls out, carefully. Both of them lower their guns but don’t put them away, yet: there’s no sign of a struggle, but the guy did just break out of an insane asylum by squishing an orderly. With a bureau that he shouldn't have been able to move. "We're not gonna hurt you. We're here to help. My name is Sam. This is my brother, Dean."
There's a loud silence. Dean can hear the wind rustling through the structure.
A deep voice suddenly speaks up. It’s coarse and raspy and sounds like it hurts coming out; he’s never heard anything like it. It sends shivers down Dean's spine.
"Dean?” the man asks. “Dean Winchester?"
(A Season 4 AU: what if the fallen angel Dean and Sam ran into was Castiel, not Anna?)
Commentary: When I saw the summary of this fic, I didn’t expect much from it. I honestly thought it wouldn’t be that good, because of the plot, but the writing on the summary was good, so I gave it a try. And ooooh boy, did it pay off!
The authors so SUCH a good job with immersion on this story - you feel everything Dean feels, because of how well they wrote it.
In this, Cas rebelled before he does in canon, just after saving Dean from Hell, and the aftermath of it is very well constructed. He ends up falling in a different time and living a human life before meeting Dean again. I won’t say much so I don’t spoil it for you, but Cas’ relationship with the Novaks is great!
Another strong point of this fic is the intimacy scenes - not just sex (although, yes, the sex), but also the kisses, and hand holding, and hugs, and looks. It’s all beautifully written and realistic (well, as realistic as one can be in SPN).
The ways the author counter the plot around the shift in the narrative is very interesting, you can tell a lot of thought went into it.