After all they've been put through, Dean's lost hope. Bobby's in a wheelchair, Ellen and Jo died for nothing because the Colt didn't work, God's a deadbeat, and they've been searching for months for a solution and NOTHING! So Dean's just about ready to say yes to Michael. But he has to see Lisa first.
"When I do picture myself happy, it's with you . . . and the kid." Damn it, his smile is so genuine! Dean acts like he's a soldier that lives for the fight, but he was just as cursed as Sam was. He DOES want more than the hunts and the one-night stands. And Lisa was more than that to him.
But the way he's wording it, it sounds like he's going to commit suicide or something, and Lisa keeps offering to talk this through.
"Lisa . . . things are about to get really bad."
"Bad how? Like your kind of bad?"
"Worse."
But even if Dean didn't go through with saying yes, I always liked that he planned on making the angels agree to some conditions. He does hold some cards in this situation.