Fic Rec: Massa Carnis by ameliacareful on AO3
Guys, guys, guys!
Do yourself a favour and go check out Massa Carnis by ameliacareful
It's a Sam and Dean Slave!fic and it is so classic Supernatural it will make you purr.
And best of all she keeps adding to the verse. Each story is a stand alone, but it follows the series in a wonderful AU sort of way. I don't want to say too much to spoil the story, but it is such a pleasure, really scratches that Sam and Dean caring for each other itch you get. Go, check it out now! Time well spent. : )