Dean never saw Castiel again. Bobby, Dean and Sam rebuilt the house and made it something of a home base. Dean hung the trench coat in an upstairs closet and forgot about it. When Bobby died, years later, and Dean was cleaning out his worldly possessions, he came across it. The tan fabric still held the stain of blood, faded to brown, and the black crust of the Leviathan's ooze. Dean ran a hand down the sleeve and yanked it off the hanger, balling it up and stuffing it in a black garbage bag. He set the bag aside for the trash and continued bagging the rest of Bobby's stuff.
With the old man's more innocuous belongings shipped off to Goodwill, Dean dragged a separate pile of garbage bags to the dumpster. He left the bag containing Cas' trench coat till last. And then he picked it up and carried it back into the house.
The house was quiet. Sam had found a kind of peace, driving around the country, occasionally working a job, but mostly just stopping at random spots to 'find himself'. He called in less and less now but whenever he did, he and Dean fell into easy habits, joking or handing each other beers without a word. Even though the house was empty, they still did their research, side by side, at the old table in the lounge, like they always had.
Sometimes, when Dean was alone, he found himself talking to Sammy. Once or twice he caught himself talking to Castiel. When he realised this, he stopped and found himself caught up in memories of better times. Or sadder times. And he could not think of Castiel with anything but fondness, or a sorrow he didn't examine too closely. What Dean didn't realise was that for every time he spoke to an absent Sam, there were three or four times he had prayed to an absent angel.
Dean grew into Bobby without really noticing. When he went into town, he wore a beat-up trucker cap, pulled low over his eyes. His groceries were one part food, two parts liquor. Even with his face more lined and his hair grizzled, women took notice. But Dean had lost the knack and ended up repelling most of them with silence or a grumpy countenance.
Dean brought the old trench coat down to the living room and set it on a chair. He gave up all pretence of normalcy and started talking to the coat as if it were Castiel. Reliving days gone by, telling Cas the latest gossip from town, complaining about Sam's infrequent visits, using small words and explaining things to the coat as though it were the clueless angel himself.
Before he went up to bed, Dean would grab himself a whisky and clap a hand on the back of the chair, lightly clenching his fingers in the fabric of the coat.
On one of his visits, Sam woke with a start and bolted out of his room and into Dean's. Sam's heart was racing and his stomach roiled. Dean looked different lying there. His face was relaxed and his hand rested on the trench coat, which lay next to him on the bed. For a split second, just before he kicked into action and went to check Dean's breathing, Sam wondered at that. He hadn't remembered Dean taking it up from the living room.
Dean blinked up at the clearest, bluest sky he'd ever seen. The grass under his feet was green and lush, the sun warm and the light bright, without glare. A lake sparkled in the distance and Dean could smell barbecue, and, under that, the sweet breath of freshly baked cherry pie. He turned his head to see the person he knew was standing behind him.
"Cas," the name was a soft exhalation.
There he was. Smiling that soft smile Dean remembered. The smile reserved for only Dean.
And he was wearing his trench coat.