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Cas sleeps these days. His stolen, fading Grace has stabilized, for now, thanks to the nephil’s influence, but he’s still weak. Weak enough that whisking away this human need is no longer a negligible expenditure.
He wakes with Dean wrapped around him, enveloping him totally from behind, chest pressed to his back, hands grasping greedily at his belly. It’s nice, being in bed with Dean. Cas has learned from experience that sleeping is a vulnerable time for humans. Dean will keep him safe. And with Dean so close, flush to him from shoulder to knee, Cas can feel Dean’s hardness against his ass. The hunger of his cock to enter the place inside Cas where the scion of clan Winchester sleeps.
Cas shifts. Presses back against him.
“You’re awake,” Dean says, a smile in his voice.
Cas hums, not ready for human language just yet. But Dean’s desire has Cas’ own cock hardening. He squirms a bit, rubbing his ass against Dean’s bulge as he works his hand down to stroke himself through his boxers. Dean gives a small answering thrust.
Cas can feel Dean’s hot breath on his neck, and he turns slightly, baring his throat for Dean’s mouth. He plunges a hand into his boxers as Dean sucks a bruise into the side of his neck and rubs up against him. Dean won’t send him away.
After a few minutes of this, this leisurely rutting, Cas pulls away. He wants Dean inside him tonight. He sits up, feeling John Winchester II - Dean had informed him that this would be the name of the child as soon as he had told Dean it was in his belly - shifting gently in the waters of his womb.
Cas strips his shirt, a secondhand tee four sizes too large (his body no longer fits anything else, and Dean won’t allow him to stoop to wearing women’s clothes), and wiggles out of his boxers. He swings his legs off the bed, slipping gently to the floor. His roundness fits well between his spread knees on the hardwood, hiding his swollen cock beneath it.
Dean insists it be this way - he won't penetrate Cas from behind, not for now. “Gross! That's where Sammy put the baby in you,” and Cas hadn't felt prepared to explain that there was no entrance to his uterus that Sam had ejaculated into, that this nephil had been created through an insemination of Grace, a wild act of creation that had taken place in his belly in the extremes of coitus, creating fetus and womb from whole cloth. Cas - sick, dying, and desperate - had been so open, vulnerable, raw in that moment that Sam’s cock had found its way into his innermost Self, a place beyond physical where God’s Light was made manifest. Such a thing could just as easily have taken place in his mouth, and indeed both his openings did after all lead to the same material location. Cas had not informed Dean, the first time he had fucked Cas’ esophagus, that his semen would mingle with his brother’s in Cas’ unused digestive tract.
Dean gazes down at Cas, eyes alight with desire. The first time they had done this, been with each other, it had been quick, shameful, unspoken. Only possible because Cas was on the outside, banished from the bunker and from the family and from sight. Cas was weak and human and pathetic before a Dean who had just breezed back into his life, and Dean had pitied him, been disgusted by him as he struggled to survive. Had gone back to Sam at the end of the night. But now, here, in the heart of the Winchester home, Dean looks at Cas’ body and sees pride - pride that his Sammy has succeeded in this most masculine of pursuits, made a man of himself in Cas’ womb, pride that the family now has a real legacy, that John and Mary and Samuel and Deanna and Henry and Millie all continue in Cas’ belly, pride that Dean is now head of a household in the most traditional sense. Dean won’t send him away.
Dean scrambles on the bed above him, and it’s a moment before he presents himself at the edge, legs spread, nude from the waist down. His cock is red and curves up towards his belly. Cas knows from experience that the head is fat enough to stretch his throat beyond the point of comfort, and his mouth waters for it.
“Come here, sweetheart,” Dean says, and he rests a hand on the back of Cas’ neck, gently encouraging him forward. Cas puts a hand on Dean’s knee, and presses his lips to Dean’s cockhead, tonguing the slit ever so slightly, just to feel Dean’s muscles tighten. He opens a bit and sucks in the head - the bitterness of precome mixes with the salt of sweat and masculine stink, and Cas is glad his Grace has failed enough that he can taste this, have the essence of Dean on his tongue and truly experience it. Perhaps now he could enjoy eating again, but he’s found hunger to be… unpleasant. He still prefers to use his Grace on that particular human need. Dean’s musk fills his mouth. His own cock twitches, still trapped between his belly and the floor.
Cas numbs his gag reflex and pushes further down the shaft, taking in everything Dean has to offer. His nose embeds in Dean’s pubic hair, and the scent permeates his consciousness. Dean’s cock fills his throat, blocking his airway, and though he has enough power to keep himself alive, he doesn’t waste any blocking the choking instinct, and his muscles twitch and jerk, his body saving itself from imaginary danger. Cas swallows around Dean’s cock, and feels Dean’s hand tighten on the back of his neck. Dean’s hips twitch forward, and Cas takes him deeper, Dean’s cock seated snugly in his esophagus.
A shift inside him. Deep. Movement in his belly. His struggle for air must have woken the baby. Cas puts a hand to his stomach just in time to feel a vicious kick. Dean grips Cas’ hair and pulls his head back just to slam it forward again, fucking Cas’ mouth in earnest, once, twice, three times, starting up a rhythm, while baby John begins to throw a tantrum inside him, pummeling his guts with kicks and jabs. A human sensation, yet it reminds him of a long time ago in another form. Once it was Dean, half-demonic and unknowing, that scratched at his insides, desperate to be free.
Cas chokes a little more, and feels his dick growing harder. He tries to grind down, writhing for friction. It’s slippery with precome, and he pushes his belly down, fucking the slicked space between his stomach and the floor as Dean fucks into him.
He fantasizes a little, wistfully, about getting fucked from behind. Wishes that Dean didn’t buy into those human taboos. He wants Sam’s big cock breaching him, filling him.
Of course, there are other reasons why Sam won’t have him anymore. He remembers walking into the map room. The shouting.
How can you want this? Do you want another kid to grow up just like we did?
What’s wrong with that, Sammy?
What’s wrong with- oh I am done with this. I can’t believe you.
I know you never wanted to be a part of this family, Sam, but I did. And so will this kid.
It’ll be a vessel for Michael, for Lucifer!
They’re gone, Sam. They’re never coming back.
And you really wanna bring our curse on another person? Bring a kid into this?
…
Besides, it’s Cas who’s knocked up. It’s his choice.
Sam had looked up at Cas, pleading. But he’d known it was a lost cause. Known that even when Cas had offered up his body for Sam’s comfort, it had been at Dean’s behest, as much to keep Sam from bolting as to keep him happy. Cas had filled the gaps between them, insinuating himself into their family as best he could. Making space for himself in their lives.
He had played keeper of Dean’s treasure. Had cared for Sam after Gadreel had left him. When Cas was still singing with freshly stolen Grace, never to be useless again. He has put himself between the brothers when Dean was a demon, played the role of Sam’s protector, of a buffer. He had given himself to Sam as a lover.
But Sam still knew. Knew he was Dean’s. Up to and including the contents of his uterus. Cas had stood with downcast eyes, and moved to stand with Dean. Sam hasn’t spoken to him since.
Still, Cas misses him. Misses the family’s wholeness. Thinks of him. Fucking Cas open and sloppy, while he chokes on Dean. While he’s already so full. The Winchester men united in his body, making use of all of him. Making a home in him. Throat and ass and womb. Sam and Dean and baby John bonded together in the family receptacle.
Cas stuffed and indispensable.
Cas feels his balls draw up, his muscles seize without his say so. That’s his only warning before he’s spilling onto the floor, body shaking, come painting the underside of his belly.
Dean catches him as he slumps, and pulls out of his mouth, cock still hard.
“Hey, Cas, you okay? You done?”
Cas nods twice.
“Okay. C’mere, then.” Dean gives him a hand standing up, and his legs are shaky. He stands at the side of the bed, and Dean presses a kiss to his belly. Baby John seems to calm, sensing Dean’s presence, his all-consuming affection, his love that overpowers everything.
Dean pulls him down. Lies beside him on the bed. Kisses the side of his neck, soft and sloppy. Rubs a hand over his belly. Dean will not send him away.
“You’ve done good, you know that?” Dean says, and light flares in Cas’ chest.
Dean gets up on his elbow, and then sits up entirely. Cas thinks he gets up to his knees, but isn’t sure. He’s too sleepy to look.
He’s almost dreaming when he feels it - the hot splatter of Dean’s come, coating his belly.
Dean makes a strangled noise. It sounds a lot like Mine.
Cas feels safe. In the bed. In the bunker. In the family.