I understand Crowley is a regular on next season of Supernatural. I suspect he knew how things were going to turn, the moment he saw the mark on Dean's arm, but this is still Dean, OMG! Dean.
He's the one to always sacrifice everything, the one to take care of Sammy, the always sacrificing everything in order to fight the cause, like his daddy (the worst father ever) taught him.
In this series there has been talk of how Dean views Sam as someone he has to keep safe/save, whereas Sam just doesn't share the same view of brothers before everything. This comes as a shock to Dean, who has been inaugurated on this view since childhood by their father.
One of the major tragedies of this show is how idolized the Winchester brothers' father is, especially by Dean, when most watchers can tell what a bad job he did of parenting and how he really fucked up his sons. *cough*
I so feel for Dean, because, yes, he has had a rough deal in life. But, Sam was also the demon boy. The one tainted by the one who killed their mother, his girlfriend, etc. He spent a lot of time as a demon-tainted one.
Dean is not the only one to have gone that route. I still like it a lot how Castiel doesn't want to be the Chosen Hero, The Good Angel, just because he feels like he isn't one. He resists labels even when the other angels try to recruit him as their front man, because he feels he failed them in his previous attempt and now feels more for his human friends than his angelic cohorts.
Going to bed now. Was overcome by feels, etc. etc. and a bit tipsy But mostly feels.