Castiel looks down, looks at Sam's large hand wrapped so firmly around his own cock, and has to screw his eyes shut to avoid a sensory overload. To feel it, to hear the slide of skin and his human's voice in his ear, is already almost overwhelming. If he were to keep watching... Castiel isn't sure he could handle it.

Even with his eyes closed, the sensations are almost too much. Castiel leans back, knowing that Sam can and will help him carry his weight, and when the coil in his guts is painfully tight, he tips his head back onto Sam's shoulder, cries out as his balls tighten and his cock twitches with each spurt of orgasm. His knees nearly give out as he's swept away on this current, unable to stop making small, needy sounds, because it's too much and not enough all at once, a current to sweet him away and a solid body to anchor him.

"Sam," he gasps. "Sam..." Because Sam is the only thing in the world that matters to him right now.