Work Text:
Grace slams both hands down on the lab table. "I just don't know why I'm not making any progress on this."
He's working on a container, a farm really, that will - hypothetically - be able to better use Astrophage's interdependent relationship with the Taumoeba and natural predator-prey dynamic. More efficient farms, with the fringe benefit of fuel replenishment and additional nourishment for Grace.
It's not enough to know that the Taumoeba eats Astrophage. He has to figure out how to keep both populations at a steady increase while sloughing off the additional amount produced by breeding. The separation mechanism is dependent on the organisms' different masses - once a certain amount of both is reached, a chute with IR light opens up, attracting the Astrophage, who are then chased by the larger Taumoeba. The smaller cells will slip through a very fine plastic mesh to the IR light, which will then deposit into a small sealed holding bucket to be emptied into the fuel tanks manually. The larger Taumoeba will be caught against the mesh, which he'll scrape and add to his food processing equipment. In theory.
These are the things that keep him busy. But today, Mary's gravity presses a little extra hard on his shoulders as he works on the mess of tubes and mesh, causing irritability, exhaustion, and an inability to focus.
It would have been easier if he had slept. Lately, he’d been waking up in a cold sweat, gasping and not knowing why. He’d always been soothed back to sleep by Rocky on the other side of the barrier in the tunnel, but waking up every hour on the hour is still pretty gnarly.
"What problem?" Rocky asks, rolling their ball from the direction of the airlock. They had just refilled their atmosphere and would be comfortable for several additional hours.
"Nothing you can help with, buddy, I'm just - frustrated with the setup of this container." He runs a hand through his greasy hair. It's been one too many days since he's washed, and he could smell himself spiraling in real time.
"Rocky see weak point in mesh. Grace not consider Taumoeba able to change shape more than Astrophage. Must find new material catch Taumoeba, better containment." They point a claw toward the mesh and the dead Astrophage in the small container.
"I know that, it's just - I can't concentrate on finding one. I should be able to do this. I understand this. I’m not stupid. I can figure this out.”
"Why Grace upset?" Rocky tilts their carapace. "Thought project going well."
Grace takes a long, slow, deep breath and feels his heart rate slow by a fraction.
“It is. I mean, it is and it isn’t. It would be if I could get my brain into gear.” He rubs the back of his neck, making a face as he twists it side to side.
”Not making any sense. Is or isn’t, not and. Maybe Grace take break,” Rocky suggests, “then experiment becomes clearer.”
“Yeah, I’d love to take a break, but I just have to get this next thing. I just have to get to a good stopping point.” He bends over the container and squints into the mesh again, pointedly ignoring that it was too fine for human eyes to see without a microscope.
Rocky stomps one of their front limbs, fist against floor. ”Grace break time now. They were being much more forward and stubborn than usual, and something made Grace want to push back a little more than he normally would.
"Could you give me like - thirty minutes?"
Rocky shifts, tapping their most fragile back limb on the ground, and goes quiet. "Grace agitated. Tired. Not sleeping. Rocky know. Rocky fix."
"No, there's nothing you can fix, I just - ah! Rocky!"
Rocky abruptly bumps at the back of his knees, throwing off his balance and causing him to crumple. He hits the floor, hard.
“Hey! I’m in the middle of something. Thirty minutes. I promise.”
”No. Now. Grace listen. You work too hard, statement, and you neglect self. This not acceptable. You take a break before your body makes you.”
“I know, I know, you’re right, I’m sorry, I just need to wrap this up.” He struggles up to his knees, checking that his palms hadn’t been scraped on the way down. Rocky had really refined their ability to knock him around without breaking skin and barely bruising, claiming care for their human’s squishy parts.
”I will make you then.” Another beat, and Grace knew he was well and truly fucked. Or at least - he was about to be. His resolve to finish the experiment crumbled, and it was stable anyway. The small amount of Taumoeba would eat the small amount of Astrophage, and he’d clean the container and start again.
Rocky pushes their claw through the flexible panel, rolling between Grace’s legs and resting it delicately on his hip. In response, Grace’s spine goes lax, his body melts into them, and he shifts his hips suggestively, minutely, invitingly.
Rocky pulls off his rolled-down flight suit, eager to expose his already-dripping cunt. These days, he rarely bothers with underwear. It's not like anyone else is looking, and the person that was considers it a good thing that he wears fewer clothes. This change was recent and abrupt, coinciding with Grace giving permission to Rocky to just… fuck him whenever. No asking. Constant access to his cunt and able to fuck him at any time without so much as a please, underwear presenting one more unnecessary layer.
Not that Grace was complaining. It had taken some time to tease out of him, but Rocky eventually found out about his free use kink. They were delighted - "Grace... let Rocky mate anytime? When Rocky want? Without ask, question?" - and drummed their front two limbs repeatedly, shifting their weight rapidly between the limbs still on the floor. Grace had expected a slight increase in sex, of course, but assumed that they would continue the same rhythm - after their work was done, on lazy days and sleepless nights - in their bunk, on the dormitory floor, in the Don't Go Crazy Room.
He had never been happier to be wrong. He’d found himself pinned up against lab tables for a rough quickie, on the floor, back up against the wall riding halfway up as Rocky pressed him further, higher, under his control, in the pilot’s chair. At this point, it was almost Pavlovian how his body reacted to the ball touching his bare skin.
The remote-control vibe came shortly after the free use agreement. Grace had never been one for shying away from brand-new things to try, and so approximately sixty seconds after Rocky showed it to him, he was on his knees following their exact instructions to insert it into himself. Then came the strap, and then the matching vibrator for Rocky that mirrored the same frequencies to both cocks. It’s Grace’s favorite, a true miracle model of engineering, and he barely contains his excitement as he hears Rocky brings it out.
He can’t see, but he knows that Rocky uses the flexible panel to bring out Grace’s vibrator and gasps as they drag it from the top of his pelvis to his cock to his dripping, twitching cunt.
”So full of blood, so heavy and ready to take me.” He groans and tries to get it further inside of him. Rocky pulls back, teasing. ”My soft little human, body singing for me whether you say or not. Hear your lungs flutter. Hear the rhythm of your heart beat, harmonize around it.”
“Please, please, oh – please, Rocky,” he’s embarrassingly worked up already, to no one’s surprise. He’s easy – he’s always been easy for his mate; he’s happy to be easy for his mate.
"I reach into your chest, I grab your squishy heart, hold in claw, fragile, easy Grace, my Grace." If he could see behind him, he would see Rocky's ventral seam split open before they slip the companion toy into themself.
“You can – oh, you can have it, ah! All of me. You can have it. I don’t even want it without you.” The pleasure builds from the solid cock in their cunt, warming him from the inside out.
Grace swears he can feel the moment Rocky turns the toy on as they both cry out, harmonizing inadvertently and slamming into each other. It was familiar by now, the sigh when they both took their respective toys to the hilt.
”Leaky human, brain gone all mush, tongue out, so pretty,” Rocky coos, and he’s burning on one side, the coolness of the floor providing no relief on the other. Rocky wastes no time pressing as deeply as they can go, ball against Grace’s ass. They roll forward with just enough force to make him moan but not enough to harm.
“Fuck me,” Grace moans, pushing back with mounting enthusiasm.
”My human toy, keep you filled up all the time, so leaky and needy that Adrian help. That mate cluster help.” There’s a moment as Grace considers it before another wave of pleasure overtakes him.
“You would – all of them? For me?” His sentences are broken and punctuated with little uh-uh-uhs as he pushes back and the cock presses in him further.
"Grace meet mate cluster,", Rocky soothes, combing a claw in his sweat-damp hair through the patch of flexible, clinging xenonite. "Mate cluster use like this too." Grace moans, cutting it off in a choke thinking about Rocky’s mate cluster.
“Tell me - oh, f - tell me about it,” he manages to gasp, grinding himself more against the solid, flat side of the ball and trying to find one of the edges to rub against his dick. His cunt pulses, drawing what he wished was Rocky deeper inside him.
”Many strong Eridians,” Rocky says, using a limb to stabilize as they shudder around the cock inside them. Grace wants more than anything to be inside Rocky, to have Rocky inside himself. For now, all he can do is pretend that the cock is their ovipositor, the warm xenonite the tightness of their hole.
”All make lots of egg when meet Grace. Human leave no choice, so sexy, claim as soon as we land.” He hears the steady drip of mercury, realizes that this is a core fantasy for Rocky, and rolls his hips again to encourage them.
“You’d take care of me, though, right, Rock? I’m so - oh, fragile, so soft,” he moans. Rocky grinds their hole relentlessly into the cock, and Grace hears the resounding crack of boulders touching. God, that sound really did it for him. The whole time he was on Earth - nothing. And now -
Now he’s being pressed onto his back, Rocky somehow above him and in front of him at the same time. They’re pumping the toy inside of them, clicks and staccato purrs somehow reverberating into Grace’s pussy, or at least he felt like it did. As the vibrator rumbled to life, he used his fingers, his feet, any purchase he could find to angle his cunt at the exact angle Rocky’s hole was. The barrier between them was warm, impossibly small, and absolute.
Rocky's the only one capable of intelligible speech at this point, huge cock splitting his sopping cunt and filling him up just right.
”My Grace, anything, anytime - show you off, my most beautiful thing, bring home from space bearing my mate mark saving my species, hold you, fill you, keep you safe.” Their tones are dropping, purrs only occasionally punctuated with higher noises. Grace can barely hear it.
He certainly hears Rocky's throbbing coos as their vibrator slides home, and for the umpteenth time wishes he could feel their insides squeeze around him. It's his hottest fantasy, most beloved in the times before he was regularly fucked into the floor when the sexual tension hung thick in the air between them.
”Hold you while you take egg clutches, carry them, help you lay them. You would think is too much. I will help you take every last one.” If he concentrates hard enough, he can pretend he’s there. He could anticipate when he would be there. He whimpers, preparing for the pleasure of being filled with eggs.
”So good for me. Perfect at taking all of us, but only I take you home to my nest. I fertilize your eggs, make all of them yours and mine. I keep you there until you lay them, fuck you and keep you safe.” Grace’s eyes roll back in his head thinking about being so cared for, so filled.
"Let me hear how much you like it. Perfect Grace. Toy Grace. Take all Rocky’s eggs.” Rocky's claw bent the flexible xenonite outwards to curl a claw on Grace's low back. He whines building gradual volume as they bottom out again and again. Grace loves it when Rocky makes him take it.
"I'm - I'm close," he chokes out, trying to move two fingers on either side of his dick.
"Hand off. Grace cum for Rocky or not at all." Fuck, if that doesn't do something to his brain. He's a toy, a thing to fuck, a leaky flesh bag only good for taking cock and being filled up with eggs.
The vibrator is unyielding and total as he grinds backwards on it. He loses focus on Rocky's words, feels the tones ring in his head as he inadvertently tries to harmonize.
"Good toy," Rocky soothes. "You take more for me, command."
Oh, God, he's going to black out and come so hard he loses his mind. He's going to really become Rocky's brainless toy. He can only whine, muffled, as Rocky repositions themself to grind against him, hips moving helplessly, automatically, tethered to Rocky's will.
He's so full, he's pushing his hips up to get more friction on his cock. Rocky's got a vibrating remote-control xenonite dildo up his cunt that's just the right side of too big, and he relishes the burn. He can feel his orgasm approaching, feel himself clench down, and began grabbing the ball, pressing his fingers flat and stretching them wide, five fingers on three. He hears Rocky’s melodic purrs speed up and knows that they’re close.
They both get this single-minded focus on each other when they’re about to orgasm, holes clenching, Rocky’s ovipositor curled around the exact same toy that was buried inside Grace. Grace feels like he’s headed towards a tunnel, the light at the end shining brightly as he concentrates solely on memorizing every bump, crevice, and patch on Rocky.
“I’m gonna cum for you,” he whispers, heat from Rocky’s hand sinking into his, and his vision whites out. Someone is screaming, and it tapers off to ragged gasps as he realizes it’s him. Rocky had made him cum so hard he screamed, and he hadn’t even touched his own dick. He presses his eyes closed and then pops them back open.
”I told you, Grace take a break.” Rocky sprawls against the front of their ball, lazily working the fake cock in and out of themselves, trapping the last rays of pleasure. They sound smug.
“Mmhmm,” Grace mumbles, “Say more about your mate cluster and I’ll take a break whenever you want.”
”Not just my mate cluster. Our mate cluster. Soon.” Tears well up in Grace’s eyes as he thinks about how steadfast Rocky’s mate cluster, how patient Adrian must be, and how much they must love Rocky if Rocky was so sure they’d accept him without hesitation. He lets the warm feeling spread through his chest as he sits up more comfortably, stretching.
”…Grace leaking again.” They shift so that they’re loafing on the side of the ball closest to Grace as he leans his forehead against it. He’s up against one wall, knees drawn to chest with one hand still against the ball, one hand wrapped around his legs.
“You keep making me leak.” His attempt at teasing is dulled by his sleepy delivery.
”You know I work on elasticizing xenonite,” they murmur as Grace’s eyelids flutter shut.
“Yeah? Awesome.” Grace shifts a little closer to the ball and settles in.
”I'm thinking flexible enough for suit. Like EVA.”
“Yeah, that would be nice.” He’s drifting off fast.
”Thinking… maybe flexible enough for ovipositor.” They knead their two front limbs as Grace’s eyes fly open.
“Rocky! You can’t just drop that on a guy!” It still sends a pulse straight through his cunt.
”… so Grace not want?”
“…I definitely didn’t say that.” He could already feel himself clenching around nothing just thinking about it. Oh, God. He was more excited to get to Erid than ever.