Castiel loved to watch.
Oh, of course he liked to participate - nothing was more satisfying than the sensation of skin on skin, of Dean’s voice breaking under the weight of his feeling, of the sweat and the slick and the smell and the taste of it all.
But he loved to watch.
Older versions of himself would be disgusted. Bored, even. He’d watched humanity for thousands of years - had admitted to himself, and to others, that the act of sex was painfully boring. Repetitive, even. Humans rutting against each other was no more interesting than someone stepping on a piece of chewed gum on the sidewalk, or sitting down in a chair to eat a meal.
They would understand eventually. The second he laid his hands on Dean, not to heal, not to comfort, but to feel him, to press him down to the bed, to touch him with reverence and desire - it was like coming home. He found himself there, his hands flitting across a body he was made to worship, his mouth tracing new scripture over skin he was made to adore.
And Dean. How he twitched beneath the heat, the power of Castiel’s attention. How he forced himself to be quiet, until a hand was placed on his shoulder and the dam broke. His voice was breathless, awed, desperate - the only kind of prayer Castiel ever wanted to answer.
He was beautiful.
Castiel didn’t know when he’d noticed. Maybe it was the first time, or the fifth. Maybe even the fifteenth. (He’d lost count of how many times they’d been intimate. Except, that wasn’t quite right. He remembered each and every moment with crystal-clear clarity. He just preferred to keep those specifics to himself.) But at some point during their relationship, he’d realized that Dean would always close his eyes when he came - overwhelmed by sensation, his hands clawed into Castiel’s back, his legs locked around Castiel’s hips - so beautiful, so stunning, and it never failed to pull him right over the edge, too.
But Castiel never closed his eyes. He kept them open. He didn’t want to miss even a single microsecond of it, no matter how many times they slept together. All of his eyes at once, attuned to Dean and Dean alone.
It wasn’t just his vessel’s eyes he watched through, either. He had many at his disposal, each eye a vibrant point of light existing somewhere outside a human plane of existence, but they worked perfectly fine where he needed them most.
Watching Dean. Watching himself. Watching the two of them together, a single body with two souls (or, the angelic equivalent). The beauty of their act together spurred him to near madness, until he gasped Dean’s name in shattered prayer against warm skin stretched taught with ecstasy.
They were beautiful there, like that. Combined into one, Castiel possessing Dean in the one way he could.
In the darkest parts of his mind, he held a fantasy of filling Dean’s body completely - of finding a space inside where he could fit himself, of squeezing himself into the cracks of Dean’s heart and healing him, loving him endlessly from within. Of seeing through Dean’s eyes. Of feeling through Dean’s skin. Of being completely and utterly wrapped up inside of him, his grace and Dean’s soul so tangled together that there was no beginning, no end.
Fucking him senseless came to an extremely close second.
To watch Dean come apart around him was a holy act. To please him, to love him, to worship him… he had been God, once. But only before Dean did he feel wholly divine.
He could spend centuries with his face pressed to Dean’s entrance, to leave gentle kisses on his cock, to lick his tongue inside and taste . Castiel took it as an act of communion.
And Dean certainly would never complain. Of course Castiel hadn’t had much hands-on experience at first, but he was an angel. He’d watched humans have sex for as long as they’d existed. He could pick up a thing or two from observation.
Plus, he's rebuilt Dean’s body himself. He had always known where to touch, where to kiss and lick and bite to make him shake with a vibrant feeling. He knew Dean Winchester’s body perhaps better than the man himself did.
And Dean’s soul, well . His beautiful body could not serve it justice. It was stunning, and scarred, and positively resplendent. Castiel could never get enough of drinking him in, of seeing Dean, of witnessing his most vulnerable moments.
There would sometimes come a point where, for all the noise he usually made, Dean would go quiet. Where he went completely soft and pliant, and allowed Castiel to do whatever he wanted.
For a being of unimaginable age, who had spent most of his life only understanding “free will” as a simple prize given to less powerful beings, the act of choosing what he wanted to do to Dean was, to put it simply, rapturous. The trust Dean placed in him, the care and affection and knowledge that he would be safe no matter what, it made Castiel feel wild.
He made sure Dean knew that. Every word out of his mouth was divine prayer, to praise and to worship and to carefully take apart the most beautiful man in all of creation.
Dean would squirm at first, when Castiel first opened his mouth and called him perfect. He curled in on himself, a red flush to his cheeks, as if he wasn’t used to those words. Castiel knew better - Dean was no stranger to sex. Dean was no stranger to weird, kinky sex. His reactions were borne out of finally being the one who gets told he is worthy of love.
To put it frankly, sex can feel a lot more monumental when you're doing it with someone you love.
Castiel was sure to take care of Dean, to command him gently and firmly, to pull him into a space where he feels safe, and comforted, and so loved.
And then to utterly wreck him, to hear him beg, to have this human who has defied his own destiny wrapped around him babbling near incoherently, desperate for release but never wanting the ride to end.
Dean was lucky. Castiel could make the ride last a long time.
And after, once they were both sated, Dean a warm and fucked-out mess on top of him, Castiel found no greater joy than cleaning up after them. Of seeing Dean’s tired, bright smile, of kissing sweat-slicked skin, of the way Dean would sometimes try to shut his legs right before Castiel pried them open to clean him up (sometimes with a towel, sometimes with his tongue - but that would usually just start another mess).
Then, finally finished, Dean would succumb to sleep. His arm wrapped over Castiel’s torso, his cheek pressed up against Castiel’s shoulder, his mouth slowly drooling onto Castiel’s skin. He looked divine in those moments. He was painfully human. Castiel could not love him more if he tried.
To witness Dean Winchester was a miracle.
It’s a good thing Castiel always would be his most devout follower.