Dean brings it up one day. They are having breakfast in the map room, Sam is out for a run and Cas has jam on the corner of his mouth. The most eloquent thing Dean can come up with after he’s been rolling it around in his head for months is, “So, marriage?” Dean tries to keep his cool, he tries not to squirm, to settle his heart rate, to not behave like a tween who’s just met her idol in person.
“Yes,” Cas says and Dean’s heart feels like it is about to jump straight out of his chest but Cas isn’t done, “It baffles me that some humans think they can speak for God when they try to withhold two people from getting married. Marriage was around before Christianity and if it was ordained by God then why do human think they can impose restrictions on it?”
Dean deflates, it’s going to be weeks before he has the courage to do this again. “Yeah man, that’s messed up.” He manages weakly.
Dean keeps his eyes on his half-eaten sandwich but he can feel Cas looking at him.
“In ancient Greece people could get married simply by holding their beloved’s hand and stating their intent to marry.” Cas says and Dean can hear the smile in his voice before he looks up.
Cas is looking at him with what Dean has fondly called his serial-killer-in-love look. No matter how much Dean loves it, it is still disconcerting to have all of Cas’ attention so firmly on him. When Cas looks at him, Dean feels like he is really seen, not just his outside, not just his soul, but all of him and Cas loves it all. It is the most wonderful and terrifying thing.
“Oh?” Dean chokes out.
“Yes,” Cas confirms and extends his hand across the table towards Dean, who takes it. “No clergy, no civil servants or pieces of paper. Just…” Cas places his free hand on top of their joined ones and his gaze becomes, if anything, more intent. “I marry you, Dean Winchester.”
Dean isn’t sure whether to laugh or cry so he does both and he adds his free hand to the pile on the middle of the table. They sit there, like a couple of dumbasses, their sandwiches shoved to the side, holding hands over central Asia, just smiling and staring.
Dean says, “I marry you, Castiel.” and he kisses the jam from Cas’ mouth and that’s that.
(They do is the modern way too, a few weeks later. They go to the court house file for a marriage license under Dean Campbell and Castiel Winchester (that way they both still get to be Winchesters) and come back the next day.
Sam is there and Claire and Jody. Dean cries again and the justice of the peace smiles when she pronounces them married. Cas kisses him in a way that is maybe a little inappropriate for a government building.)