"I don't see the point in this," Castiel said as Dean deposited another 224 grains of sand on the steadily growing pile that covered him neck to foot, the granules even sliding inside the ‘swimming trunks’ that Dean had suggested he wear.
"It's fun, Cas."
This was true as far as Castiel could tell because Dean's soul had brightened to the point that even his eyes shone with the light of his joy. Castiel did not always understand why Dean found something amusing; he'd gotten better at it over time, had wished to learn and thus had learned what would set Deans soul ablaze and why, but it was an ongoing process and sometimes comprehension eluded him utterly. This was one such instance.
"Covering me in sand is fun?"
"Uh-huh. So is being covered," Dean said as he reached for more sand.
Castiel opened his mouth to dispute this, but Dean looked at him in exasperation and said, "try." So Castiel did, focussing his attention on the weight of the sand pressing down on him, hemming him in; examined its temperature, so cool compared to the heat of the sun that still warmed his face, cool also compared to this body's temperature.
"It's a little like being inside a vessel," Castiel concluded. If one could be inside a vessel while inside a vessel already, that was.
Dean blinked at him in surprise. "Really?"
"Yes." Castiel didn't add that it was limiting also, or that he found far less enjoyment in this than he found in being inside a vessel. Having a physical form allowed him to interact with Dean, after all, while being covered in sand didn't benefit him in any way. "Why is it fun for you, Dean?"
"Because when you cover someone with enough sand, they can't leave or move -- yes, I know, Cas," Dean growled, once more cutting Castiel off before he could say anything. He pointed his index finger at Castiel's nose. "You can't leave or move."
"I can't leave or move," Castiel repeated dutifully, even though he could, of course, but Dean seemed to expect it, and Castiel was gratified to learn he guessed correctly when Dean's soul grew brighter immediately upon hearing Castiel acknowledge this...command.
"That's right." Dean grinned, then climbed atop him, legs on either side. He leaned forward, hands cupping Castiel's face, mouth hovering so close above Castiel’s own that they were breathing the same salty, wet air. They remained in this position until Dean closed the distance, letting lips brush lips, softly, once, twice, many times; increasing the pressure and the length, then decreasing them at will, pulling away entirely at last, and Castiel moaned and wanted to follow and --
Dean ran a thumb over Castiel’s bruised lips, desire and mirth clear in his eyes. “Having fun?”