My immediate reaction was 'there must be!', but I can't think of any that doesn't involve a third party who gets romantically involved with the victim.

There are factions in fandom who think that one brother is canonically an abuser to the other, though, so you might find them writing that kind of fic. The downside, obviously, is that anything they wrote would probably be pretty character-bashy to whichever Winchester is the villain.