[ strangely enough, however, Dean could relate. Hell, how often had he goaded Sam? Tried to break things off? Just because they were brothers didn't mean they were supposed to stick by each other 24/7 watching each other's back.
But then things went to hell (a little more literal then Dean liked to admit) and he found out how fucked up and stupid that idea was. Shit, even Lucifer congratulated him on being a screw-up. Now that's just wrong.