Crowley couldn't help but smile. As hard a nut as Dean Winchester was to crack, he knew that this would be the one thing to undue him. The taking of Sam's life, whether by his own choice or not, would be his unmaking. Sam, Dean's brother, the only man in the world that he would willingly give his life for, was now dead at Dean's own hand. Putting the First Blade in his hand was just a task, but the taking of his brother's life was on Dean. Yes, the blade made him a demon, but that didn't force Dean to kill Sam. That was Dean's own doing. It was simply Dean's reaction to the Blade, becoming a demon, but it was his own darker desires that had led to his taking of Sam's life. His anger, his annoyance, and his own dark desires brought him to the brink; to the place in which he erased his brother's existence. Once Dean Winchester had been more than Crowley could control, but now, now he was nothing more than another demon. He was an underling to be trained; perhaps to be brought up as the rightful heir to the throne of Hell.