Castiel/Balthazar - Balthazar is a ghost - human or angel - who loves to come down and scare a few kids when he can. Halloween is the best opportunity, and he comes across a few college kids who think it's funny to egg other fraternity houses. Dean and some other guys run off, but Cas (who was against it all aling) falls over on his escape. They end up talking and either fluff/sexy times, it's up to you :D