Are you looking for general stories or dean/cas ones? I’ll throw in a bit of both. And a bit of holiday spirit.
A Flash of Harmless Lightning gen, pg, 4k. Summary: After a year, Castiel still doesn’t appear to be adjusting well to being human. Dean tries to help, and finds the solution in an unexpected place.
Asunder dean/castiel, r, 23k. Summary: Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder. (Matthew 19:6)
The Cold of Flesh and Stone dean/castiel, nc-17. Summary: “Maybe I’m sick of spending Christmas elbow deep inside something’s intestines, or standing in a grave somewhere in the freezing cold waiting for bones to burn.”
The Ghosts in the Machine dean/castiel, nc-17, 10k. Summary: Dean gets visited by ghosts of Christmas past, present, and future. Sort of.
Good Things Do Happen dean/castiel, pg. Summary: A Winchester Family Christmas, 2010. AKA, Best zombie Christmas ever!
An Unconventional Kind of Place (wip) pre-slash, pg. Summary: Dean runs a day care center for human and angel kids, the first of its kind. Castiel is a parent.
Filling the Blanks dean/castiel, pg, 5k. Summary: He died first, and it was thirty years before Dean followed. Thirty years is a long time, and Sam finds that he has a lot of gaps to fill.