The pairing is not surprising given that the characters obviously have a long and close history. Balthazar is of course an angel with a rather voracious sexual appetites by his own reporting.
- Rec list of Castiel/Balthazar fics
- Balthazar and Cas, a ship made in Heaven by balthazarsacolyte (April 2011); archive link
- Why I ship Castiel/Balthazar by songsofthestars (April 2011); archive link
Communities where you may find fic with this pairing: