"Good," he says, as always baffled by the idea of loving more than one person and glad that Barry (for all Castiel seems to not get along with him) is Derek's best love.

He wouldn't be able to stand the idea of being a relationship that was otherwise.

"Well, then, it seems to be that cohabitation and eventually marriage would be the next obvious steps. I am glad for you. You smile much, much more than you used to."