Awakening Outside Rivergrove by fanspired on Ao3. Part of a triology but can very easily be read as a standalone.
Summary: After a night of hard drinking Sam wakes up to find himself cuffed naked to the bed, and his brother in the grip of a demon with an unorthodox agenda. Masks are ripped off, walls crumble and feelings are exposed as Sam and Dean are forced to confront their hidden desires.
Context: Season 2, between CROSSROADS and CROATOAN.