He didn't want to get married. Especially not to the King of Purgatory, Richard 'Dick' Roman. Castiel enjoyed being free, he enjoyed the times he would escape the confines of the castle and explore the kingdom of Heaven before his father, King Charles 'Chuck' of Heaven sent soldiers after him to bring him home. One of Castiels favourite places to go was to the docks, the hustle and bustle of merchants making it a lively experience while the waves of the ocean calmed Castiel, allowing him to dream of a world far far away from the one he was being forced to live.
The Impala owned the ocean, in the captains personal view. She just looked so beautiful riding the waves. Terrifying to other sailors who got in her way, but beautiful to Dean Winchester. Being a pirate, one would think that his life was thrilling, filled with excitement, fighting, killing, purging, stealing, and adventure. But for the most part, Impala was calm against the waves, no exciting new adventures for Dean Winchester on the horizon. Only him, his ship and his crew, free to sail off into the sunset every evening. Until...
Cas, Dean, and Sam have been hunting together and splitting off to take smaller jobs. The story starts with the three of them on three separate hunts. Cas is human and wounded. He shows up at Dean's motel in need of help. What proceeds is the two of them meeting up with Sam and going on an involved hunt, over the course of which Dean and Cas slowly figure out their feelings for each other. Lots of awkwardness (in a good way), some mild angst, comfort, and eventually fluff and smut.