Hey I got a new challenge: I must have read this fic a LONG time ago and never saved it so here's what I remember...
-I'm fairly sure I read it on AO3
-It was a Firefly/Supernatural crossover
-The fic basically had the exact same plot line as Firefly, but the characters from SPN were subbed in.
--Dean Winchester was the captain
--Castiel was the preacher...?
--Sam Winchester was "River"
--The ship was named Impala
-Dean was the captain of the ship and the fic started with Dean letting the doctor (I don't remember which character was subbed in for him) on the ship to take him to another planet. Dean was suspicious of the doctor so later Dean followed the doctor when he was sneaking into the cargo hold. I remember that the doctor's luggage slid off and hit the floor hard and the doctor was angry about that because inside the box is Sam, who was subjected to cyro for transport. Sam and the doctor were running from the Alliance and the doctor is trying to protect Sam.
-It was a WIP when I read it and I don't know if it was ever finished...
Thanks to all in advance! :)
(edit) FOUND: Home Is Where The Heart Is by JCRGirl
http://archiveofourown.org/works/1151553?view_full_work=true