Vestige

He had begged Cas to take the Mark from him.  In a moment of weakness, he had begged for a solution, for a bit of angelic power to scrub him clean and save him from a doomed fate, but Cas had only given a sad shake of his head and explained it was out of his power to do anything.  When all else had failed, Dean had hoped that Cas might have been enough, and his knees had almost buckled with cold dread when even his angel friend could do nothing.In a fit of barely concealed hysteria, Dean had suggested cutting out the Mark, sloughing it off his skin, but Cas had hurriedly explained that the Mark was merely a physical aspect of the curse, and cutting it off would do nothing.  It would not rid Dean of the images that tormented him, and it would not wash away the feelings of savagery Dean tried so hard to keep under wraps.That was when the last bit of hope Dean had clung to dissipated and he concluded he was a monster.