The Ghost Of You

Tag to 10x09 "Things We Left Behind" - As Dean descends again into the violence of the Mark, Sam's worst fears come true. But Dean is in shock, and all Sam can think to do is to get his brother home. Along the way, however, as his own levee breaks, an anguished Dean finally admits to a far more desperate hell: that, as demon, as "that thing," he'd tried to kill his Sammy.