When he wakes on the first day of his monthly heat, Keith feels like he’s been set on fire.
Insomnia. He sweats awake at 3 a.m. and rolls over three times. On the third toss, his forearm makes contact with hot skin.
Shiro. The man next to him sighs in his sleep, half-waking to take Keith’s wrist in a loose grip, holding it to his chest like it brings him comfort. Keith wants nothing more than to curl into him, to breathe in his scent, to kiss him all over, but it’s too hot in here. It’s too hot even under his own skin, so stifling he wants to crawl out of it.
Keith extracts his arm from Shiro’s grip, slowly, and leans down to press his mouth to his cheek. Shiro takes a deep breath through his nose, drifts back into deep slumber. Keith can taste the light, sweet film of perspiration from his partner’s skin still on his lips; he licks them, drags himself out of bed to escape the crush of desire.
He leaves the bathroom light off, turns on the shower. It’s like standing in a cooling rain at night; it soothes him, but under the surface of his skin his flesh still simmers. Ever since his Galra heats started coming some years ago now, the Blades first had the foresight and mercy to give him injections to stop the heat cycles during missions; then, even when Keith had returned to Voltron, it had been useful to keep up with the medication to stave off the misery that came with being hot, horny, and irritated to a maximum degree – and very, very, dangerously fertile.
But the plans they’re making together are different now. Keith and Shiro. They’ve been through everything together. Fallen in love. Keith had to wait a few more years for Shiro to realize it, but when it happened, it was even more wonderful than he could have imagined. They were happy. Got married in front of all their loved ones, moved in together…
There was a night a few weeks ago where they’d fucked without a condom. Keith was underneath him, holding him close in his arms, their hips rocking each other gently as they kissed. It wasn’t kinky, wasn’t rough, wasn’t out of the ordinary; just quiet, tender, two people in love and part of each other.
“Cum inside me,” Keith had whispered, hot against his neck. “It’s okay.”
At breakfast, Shiro had set down their coffee mugs, sat down next to him. “Can we talk about it?”
Keith smiled, smoothed Shiro’s silvery hair off his temple. “Yeah.”
Keith stopped getting the injections.
Now, it’s as if all the heat cycles he’s missed for four years have all come back to bite him at once.
He lathers his hair, tries to focus on something other than the heavy throb between his legs. He’s so wet all the time now, without even provocation. Sleeping next to Shiro has become almost unbearable during these bouts; he can’t even hear him breathe, can’t even feel the hard muscle of his chest and abdomen against his bare back, can’t idly handle a soft kiss to the nape of his neck without begging to get pinned and fucked hard.
He worries it’ll drive Shiro away. So he isolates.
Just when he thinks the cool shower might let him go back to bed, the bathroom door creaks.
“Keith? Are you okay?”
Keith shudders at the low voice, a deep tingling that ripples in his cunt.
Keith swats the water from his eyes, smoothes his soaking hair back. Shiro’s shadow lingers on the other side of the curtain.
“Can I join you?” It’s almost shy, still. Keith revels in it.
He edges back the curtain, slips an arm around Shiro’s neck. “C'mere,” he breathes.
They hold each other under the spray, Shiro’s arms around him, nibbling playfully at his lips, licking them. Keith moans into his mouth, groveling, pathetic. He’s afraid if he lets go of him, he might pass out.
“You feel all right?” Shiro asks, gentle, lips brushing the shell of Keith’s ear.
“Horny,” Keith mutters. “Sorry. Really, really, really fucking horny.”
The older man kisses his neck, tangles fingers in the hair there. The other arm, the floating prosthetic with the soft blue glow, pulls him closer.
“Shiro,” Keith moans. “Shiro, please…”
Shiro takes his shoulder in his human hand, gentle but with decisiveness. He turns Keith toward the shower wall, presses him against it. Keith hisses at the cold shock of the tiles against his nipples, his belly, and Shiro soothes him with kisses down the side of his neck. His hands travel the length of Keith’s sides, ribs to hips, his flesh hand kneading one of Keith’s firm globes. Keith can’t stop panting, now; his breath is hot against the chilled ceramic. When the warm velvet skin of Shiro’s erection bumps the back of his thigh, Keith strains to stand on his toes, to lift his ass higher.
The invitation is enticing, to say the least. Shiro massages thighs, ass, hips. He spreads perfect globes with his thumbs to admire the pink gem-like center of Keith’s pussy, glimmering wet from something thicker and far more delicious than water.
“I’m ovulating,” Keith blurts out, a warning.
Shiro kisses his shoulder, a proud little smile that Keith can’t see, but can hear. “Good.”
A curious finger slips between soaking folds, and Keith gasps at the intrusion, his breath warming the tile under his mouth. He keeps his face pressed to the wall, his sounds echoing around the shower as Shiro tickles his throbbing hole. He’s only one finger in, and Keith thinks he could come.
“You’re so wet,” Shiro remarks, quiet with awe. “Keith… Wow…” He makes little circles inside him with his finger, teasing.
“I need you,” Keith whimpers. “Please, baby, I need you.” He’s almost weeping.
“I’ve got you, sweetheart.” Shiro nuzzles at his ear, casually adds a second finger into Keith’s leaking slot. The pleasure is so intense Keith’s hips stutter against the wall. “You want my cock?” It’s a husky whisper, barely even a question.
“Give it to me,” Keith pants back.
Shiro gives himself a few tugs. Keith braces his forearms against the wall, arches his back at some beautifully impossible angle, glances back at Shiro with hazy eyes that spark yellow and violet like a couple of live wires.
Keith cries out when Shiro’s thick girth splits him open, parting him in two, opening him wide for the breeding his body craves. Shiro tries to take it slow at first, but they both quickly find it dull; Keith props a foot up on the lip of the tub, and Shiro presses closer, fucks into him fast and hard from behind. It’s the kind of wild, raw thing Keith’s been trying to get out of his head all night. Now he doesn’t have to.
“Fuck, yes, Shiro,” he yells over the splash of the shower, his words punctuated by Shiro’s heavy-hitting rhythm. “Ah, hah, fuck, yes, baby! Baby…” His eyelids flutter shut as his pupils roll back. Shiro takes a handful of his long black hair in a fist, tugs it just right, arrests Keith’s neck so he can bite it. Hard. He knows what Keith wants.
“I’m gonna fill you up,” Shiro grunts, his hips smacking wetly against Keith’s ass as he fucks him rough against the wall. “Take it, take my cock. You’re so beautiful.”
Keith’s thigh climbs higher up the wall, foot dangling in the air until Shiro turns him around again. Keith smiles, open-mouthed, blissed out as Shiro lifts him effortlessly. His ankles brace against the bigger man’s shoulders, Shiro’s hands under his ass to keep him suspended as he enters him again. He’s so deep this time, his cock bobbing expertly in just the right places, swollen head teasing cervix and the supple bend of his shaft pressing all the most sensitive buttons.
“I’m gonna cum in you,” Shiro rasps, decreasing his pace enough to speak, enough to drive Keith toward his climax with the slow, deep fuck that he likes best. “I’m gonna breed you right, just the way you like it.”
Keith feels like he’s floating; pleasure pulses inside him from labia to navel. Shiro’s dick rolls heavily in and out, fucking that sweet spot behind his mound, turning his legs to trembling gelatin. Velvet-skinned balls heavy with cum, ready to bust, slapping tender skin between pussy and ass.
“It’s so good.” Keith’s sobbing. “Please, please, give me all of it.” He kneads his clit with two fingers, almost savagely, his gaze bright in the near-dark. “I love you. I love you…” He finds the right rhythm, playing rough with his throbbing button until the pleasure building up behind his pubic bone bursts. He shouts, digging fingernails viciously into Shiro’s shoulders as pleasure tears through him.
“Fuck,” the bigger man grunts, rocking faster on his high. “Keith… fuck… I…” He comes on a primal growl, clutching at fistfuls of Keith’s ass, his whole prick buried and twitching and spurting seed. He feels each ejaculation, deep pulses of pleasure in his abdomen; once, twice, three times. Keith’s pussy tightens, holds snug around his length, milks every drop.
They catch their breath, even Shiro’s well-muscled thighs shaking a little with the effort to keep standing.
“My knees,” Keith groans.
“My back,” Shiro responds, letting him down.
Their laughter dissolves into kisses. Shiro squeezes ass cheek just because. Keith nuzzles his cheek, his jaw, his neck, gnaws at the firm curve of Shiro’s pectoral muscle. Shiro hums, kisses him, turns off the shower.
“You know I’d love to clean you up,” Shiro starts, but Keith jumps over the wall of the tub and into a towel.
“No. Uh-uh. Don’t touch anything. I have to lie down, it’s already leaking out.”
Shiro sighs. “I’m pretty sure the odds are still good if you sta-”
“Nope!” Keith’s already out the door and back to the bedroom, rolling himself like a cocooned butterfly in the bedspread, his body temperature suddenly feeling closer to normal than it’s been all night. “Thanks, babe, you’ve been great!”
Shiro laughs to himself, finishes rubbing down. He’s tired again; he isn’t the 5 a.m. riser he used to be. Maybe that’s a good thing.
He slips back into the bedroom, and Keith – suddenly needy – pulls him back into bed and settles against his chest. He’s warm; Shiro sighs, cradles him. “I love you, Keith.”
But, thankfully, Keith’s drifted into the sweet embrace of satisfied sleep.