Sam found a way to get rid of them for almost a month at a time, a spell that lasted until the first night of the full moon.

The Winchesters have been subjected to a lot of things in the name of hunting, but the result of a spell-gone-wrong on their latest case is still pretty high on Dean's weird scale. While their father is out searching for a way to undo the magic, Dean's stuck in a cabin in the middle of nowhere, trying to deal with his bitchy teenage brother and his own increasingly un-brotherly feelings toward him. Who'd have thought Sammy growing a pair of giant bird wings would be the least of his problems?