Castiel/Balthazar
From Super-wiki
Castiel/Balthazar slash fanfiction pairs the characters Castiel and Balthazar in a romantic or sexual relationship.
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.
Sometimes this pairing is considered incest - also called angelcest - depending on whether angels are seen as siblings or not. Balthazar does say to case "we're brothers".
Links
- Rec list of Castiel/Balthazar fics
Communities where you may find fic with this pairing:
