Nightmares After Hell

"It's been a year since Dean went to Hell. Yet he is still having nightmares of all the souls he tortured. Of all the terrible things he did to those souls. Sometimes, he thinks that his nightmares are from those souls. They want to make him suffer. It's almost like they are trying to get back at him for tearing their souls for 40 Hell years."

Or the one where:
Dean was having nightmares a year after he came back from Hell and one night, he had a terrible nightmare and Cas came to comfort him.