Jimmy was under six feet tall and told his wife that he loved her every morning. Castiel transcended mortal measure and could not love a fragment above the whole of creation.
Jimmy is flesh and blood, surviving intangibility because Castiel can buffer minds and preserve sanity. Castiel is grace and will, surviving physicality because Jimmy can temper grace and translate life.
Their union is one of glory and pain. Jimmy breathes and Castiel sustains and they dance in sinew and light.
But JimmyandCastiel is a man in trenchcoat armor and tired ties, and they avoid his gaze in the mirror.