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At the Apex of the Paschen Curve

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Paschen's Law is an equation that gives the breakdown voltage necessary to start a discharge or electric arc, between two electrodes in a gas as a function of pressure and gap length. At higher pressures, the breakdown characteristics show as a function of the product (usually non-linear) of the gas pressure and the gap length. This is the Paschen Curve. As the pressure is reduced, the curve of breakdown voltage versus pressure reaches a minimum, making it easier for an electric arc to form. 

 

“It’ll be a quick there-and-back,” Pidge says, not looking up from her monitor. “Won’t even need the teleduv.” Her fingers fly over her haptic holographic keyboard, the glare of her screen reflecting in her glasses. A flick of her wrist sends the data up to the main screen, and everyone turns to look at the display.

A planet looms, its surface overlaid with topographical mapping and a blinking dot marked above the equator. “This is Tyvi.” Pidge taps her screen and the image zooms. “There’s a place to land about a click and a half from the target area,” she says, and the image shivers as it sharpens into a rendered likeness of the surface of the planet.

“The planet’s got a breathable atmosphere, and as far as I can tell, the big feline-esque predator doesn’t live on that particular continent,” Hunk says from his console. More data flashes up on the main screen, showing the chemical makeup of the atmosphere as well as other climate data. “It’s sort of earth-like,” Hunk says, thoughtful.  

“Maybe if you’re only looking at atmospheric makeup,” Pidge argues, tossing another bunch of data at the main screen. Shiro recognizes barometric pressure readings and wind speeds. Hunk disagrees, loudly, and Shiro tunes them out.

Beside him, Keith stands in parade rest, hands clasped loosely behind his back. Shiro tries not to notice the line of his shoulders beneath the jacket, or the way Keith’s lashes are like soot against his skin when he blinks. Marshalling himself, Shiro turns to look at Allura. They share a look. After a moment, she looks away from him and back up at the main display. She frowns, and Shiro follows her gaze. What was previously an overlay of the target region is now a list of ways the planet is the same and different from Earth.

Allura sighs, squeezing the bridge of her nose between thumb and forefinger. “Okay,” she says, interrupting Hunk and Pidge. They subside quickly. Allura scans the assembled paladins. “Keith? You’re up.”

Lance’s disappointed noise is ignored. Keith nods, and steps over to Pidge. He leans down towards her screen. “What am I looking for?” He asks, and Pidge points at her screen. “Oh,” says Keith, “huh. How much of this stuff are we gonna need?”

“Couple pounds,” Hunk says, ambling over to Pidge’s console as well. Pidge looks up, brows furrowed. “Maybe five pounds?” Hunk amends.

“Okay,” Keith says, and then straightens. He meets Shiro’s gaze.

“I’ll go with Keith,” Shiro says. Allura raises one delicate eyebrow. Shiro doesn’t dignify it with any kind of response. “Pidge?” he asks, “can you push the data into the Lion navlink? We’ll take Red.”

“Sure,” Pidge says absently, but he can see she’s already doing what he asked.

“What other planets are in the system?” Shiro asks, and Pidge throws that data up on the main screen. Allura steps off the teleduv pad and comes to rest beside Shiro.

“We’ll keep the castle in a high orbit around this one,” she says, pointing out a gas giant with a ring system that rivals Saturn’s. “Good cover and the rings will provide interference against detection from Galra scans.”   

 

–-

 

The planet’s surface is a mess of greenery. The trees are several stories high, and as they close in, Shiro sees that a kudzu-like kind of vine covers everything but the tallest of the trees that rise through the canopy like sentinels. A flock of birds erupts from the top of one of the trees and Keith banks hard, pulling Red out of their flight path. The birds rush past the Lion’s viewscreen in a riot of colour. Shiro reaches for the bar above his head, and feels the servos in his hand whine as he grips the back of the pilot’s chair in a bid to keep himself upright until Keith levels them off.

The navigation data from Pidge shows they should head for the mountain range Shiro can see ahead of them. “Can you see anywhere we can set down?” Keith asks, turning to look at Shiro while he lets Red decelerate until they are gliding over the tops of the tallest trees. Shiro turns to the bank of monitors beside him, looking for a good spot that’s within a reasonable hike of their destination.

“Here,” he says, “heading 5.265.” Keith nods, and they drift gently to the right. “About three clicks? Should be pretty easy to see from up here.”

The clearing appears as Shiro had said, and Keith sets Red down in the centre. The Lion settles into a crouch. While Keith runs the usual atmospheric checks, Shiro does a thorough sweep with the Lion’s long range scanners. Even though Pidge said the atmosphere was breathable, and Hunk said the big predator doesn’t live on this continent, it’s better to have more information than less. His scan finished and devoid of anything concerning, Shiro watches Keith’s hands, quick and light-fingered and confident as he combs the data for what he needs to make sure they’re safe to disembark.

Finally, Keith nods and turns to Shiro. Excitement bubbles in Shiro’s stomach. It’s been a long time since they’ve been able to get down onto the surface of somewhere new.

“You wanna go first?” Keith asks, something knowing in his face. Shiro thinks about demurring but he does really want to go first. First human on Tyvi. He was the first out of the capsule on Kerberos too, and Shiro figures that putting his feet down on a new planet will never get old.

Keith follows Shiro down the ramp. Shiro hesitates for a brief moment before stepping off the ramp and onto the surface. His boots sink into the ground cover. He takes a few steps, before reaching up to pull off his helmet. Keith gives him his moment, hanging back while Shiro turns around in a full circle, pulling alien air into his lungs. Each breath feels energizing.

“Air’s a little more oxygenated than we’re used to,” Keith says, having pulled off his own helmet.

Safe to breathe, the air might be, but it’s still a wall of heat. Shiro can taste the humid damp on the back of his tongue every time he breathes in. At least the armour has its own climate regulation, Shiro thinks, as he pulls his helmet back on, the latches clicking softly. He re-settles his pack on his shoulders, watching Keith sling his own on.

“Whew,” Keith says, over their commlink “I know hot, but this is something else.”

“Oh yeah,” Shiro agrees, “reminds me of summers in Tokyo - the humidity just sucks the life out of you.”

“C’mon,” Keith says, looking down at the display on his wrist comm, “should be this way.”

Shiro lets Keith set the pace, and they head out of the clearing and into the jungle. They don’t talk much, but Shiro doesn’t mind the silence. It reminds of him of taking Keith hiking during a long weekend. They’d driven out to the Grand Canyon early on the Saturday morning, and spent the day on the trails. They’d ended the day watching the sunset, sitting on the edge of a sheer drop. It had been a lovely day, and then two weeks later, he’d been watching the Grand Canyon get smaller and smaller as he and Matt and Commander Holt had broken atmosphere.

Ahead of them, the trail starts to climb. Keith doesn’t slow his pace and they cover ground quickly. The trees start to thin, and the trail turns from a path into a scramble over bits of rock that have fallen off the cliff face that runs along to their right, it’s face a jumble of ledges and crags. Trees and shrubs hang precariously where ever they can find purchase.

They crest a ridge and Shiro turns. The valley falls away behind them. “Oh,” Shiro says, and he hears Keith stop. They take in the view together. “Reminds me of the Olympic National Forest,” Shiro says, then, “I’ll have to take you when we get back to Earth.”

“Do you want to stop for a bit?” Keith asks, “we’re almost all the way there.”

“No, I’m good,” Shiro says, “let’s keep going.”

They continue on, Shiro in the lead this time. The HUD in his helmet shows him their route with blue dashes stretching out in front of him and Shiro follows the plotted course. Their destination is just over the next rise.

“Should be just here,” Keith says, coming up beside Shiro.

“What are we looking for again?” Shiro asks, and Keith holds up his wrist. The plant showing on his comm has dark green leaves, and brilliantly purple flowers. “Pidge said it smells kind of like wintergreen? Sort of minty, I guess,” Keith amends, in response to Shiro’s unasked question.

“Alright,” Shiro says, “let’s spread out and see if we can find it.”

They split up, and head off the trail and into the underbrush. Shiro keeps one ear tuned to his commlink as he searches. Shiro clambers over a fallen log, dropping down softly onto the other side. He hears Keith grunt through the comm. “You okay?”

“Yeah,” Keith answers, after a moment, “just missed my footing.”

Shiro leans against the log, and looks up at the canopy. The trees don’t have crown shyness here, they grow into each other, on top of each other, fighting for whatever light they can get. The pseudo-kudzu climbs every trunk and wraps around every branch, giving every tree the impression of wearing a form-fitting coat. Shiro pushes off the log, striking out in the direction of where more sunlight seems to get through the canopy.

“I think I found it, Shiro!” Keith says as Shiro’s skirting the edge of a boulder. It’s surface is covered in moss and lichens.

“On my way,” Shiro says and backtracks. He pulls up Keith’s signal and follows the blinking marker back to where they split up and then further in the same direction. Keith is waiting, crouched in front of a plant. It has dark green leaves, and the buds, while tightly closed, definitely have a purple hue.

They compare the image sent by Pidge to the plant in front of them. “It looks right,” Shiro says, “but we should send a sample up to Pidge to be sure.”

“Agreed,” Keith says. He plucks a couple of leaves off the nearest plant. Shiro shrugs out of his pack, and pulls out the little field sampling device Pidge packed them. Shiro turns on the scanner. Keith hands Shiro the leaves and then stands, tapping into Red’s commlink through their suit comms, and using it to boost their signal out to the Castleship.

Shiro focuses on the task in front of him. He drops the leaves into the small dish, and waits for the machine to spit out the results. Keith taps him on the shoulder when the link is established and Shiro uses his wrist comm to piggyback Keith’s signal and send the results up to the Castleship.

Pidge’s answer comes back after nearly five dobashes. “Yep! Definitely the one we want! Careful not to crush the leaves, I want as much of the oil as we can get.”

Keith acknowledges and Shiro packs up the scanner, before handing Keith the other pack. They make quick work of picking enough of the plant, stuffing it carefully into their packs.

The walk back to the Red Lion is strenuous. Keith and Shiro each carry a pack laden with the fruits of their expedition. Shiro can feel the straps digging into his shoulders and he focuses on putting one foot in front of the other, even as sweat beads along his temples and runs down his spine.

Keith scrambles up an outcropping of rock and lets out of whoop of joy. Shiro heaves himself up after Keith and feels the smile growing on his face. The river they’ve been following bends around the cliff here and pools, clear and still, at the base of the outcropping.

“Let’s take a rest,” Shiro suggests, shrugging out of his pack and letting it fall to the sandy shore. Keith follows suit, and then pulls off his helmet.

Shiro squats next to his pack and rummages in one of the outside pockets for a handful of Hunk’s version of protein bars. They are lurid purple and taste strangely of sage, but they do the trick. He passes one to Keith before sitting down beside his pack, and tugging off his own helmet. Shiro takes a deep breath, feeling the rich air liven up his blood. He rocks back into a seated position, then leans back, propping himself up with one hand thrust behind him.

Keith sprawls next to him, and they eat in silence. Shiro finishes one energy bar and goes back for another. He offers a second bar to Keith but Keith shakes his head, pulling a long draw from his canteen instead. Shiro doesn’t watch the line of Keith’s throat work as he swallows, but only because Shiro already has that particular movement catalogued in his brain. He focuses instead on unwrapping his energy bar.

The sun is gentle on this planet, the sky hazy and the light diffuse. Keith sits up straight and wipes his mouth with the back of his hand. “We should go for a swim,” he says. Shiro blinks.

“A swim?”

“Yeah,” Keith says, “c’mon, you know you want to.”

“We have to get back–”

“We have lots of time,” Keith says, waving his hand at where the sun hangs, still high in the sky. “Days are longer here, we’re not gonna run out of light anytime soon.”

Shiro looks out over the water, and then back up to the sky. He looks over at Keith. Keith’s grin is a slow bloom and sly with implication.

“Bet you won’t do it,” Keith says.

“Bet me what?” Shiro asks, already giving in. He wasn’t ever going to be able to resist, but now that Keith’s made it a competition, he’s helpless.

“Bet you that if you get into the river first, I’ll double up and carry your pack back the rest of the way to Red.”

Before Keith is finished speaking, Shiro is already stripping off his vambraces and leaving them in a clattering pile. Keith pushes himself to his feet and they race to get out of their armour. The pile at Shiro’s feet grows and then topples over when he drops his chest plate on it. Keith is already down to his undersuit, but he can’t quite snag the zipper at the back of his neck, so Shiro catches up.

Shiro runs for the shoreline, hearing Keith’s footsteps pounding behind him. They hit the water at the same time.

The water is aching cold and a welcome change from the heavy heat of the jungle air. Shiro sinks under the surface, rubbing his hands through his hair and then surges up, breaking through with a splash. Keith follows a moment later, shaking his head like a dog. Water droplets fly everywhere.

“I win!” Shiro crows, and Keith squawks in disbelief before pushing his hands through the water in Shiro’s direction and sending a wave outward. Shiro splutters and sends one back. Keith dodges the spray with a bark of laughter and paddles out of Shiro’s reach.

Shiro licks his lips. The water tastes sweet and deeply cold, like it used to in the spring fed pond at his grandparents’ cottage in the mountains. The taste bursts on his tongue and makes Shiro want to guzzle down handful after handful. He contents himself with cupping his palms and drinking deeply.

“Do you really think you should be drinking the water?” Keith asks, concern maring his previously carefree features.

“Was safe enough to swim in, wasn’t it? Besides,” Shiro says, licking droplets off his lips, “it tastes good.”

Shiro lets himself drift, floating on his back, legs dropped below the surface and his arms spread out at his sides. Around the pool, the jungle isn’t silent. Birds and other animals call, their polyphony half-deadened by Shiro’s head being half underwater. He breathes deeply, staring up at the sky. Somewhere to his left, he can vaguely hear Keith moving about in the water, but it doesn’t sound panicked, so Shiro leaves him to it.

The water is like a caress against Shiro’s skin and he can feel his eyes growing heavy. The buoyancy of the water is different than on Earth, he notes, as has no trouble keeping himself afloat with very little effort. He’s not sure how much time passes while he floats, but eventually, the chill of the water seeps into his bones and Shiro rights himself, touching his foot down to the bottom of the pool. The rock floor is smooth against his feet.

Standing in water shoulder deep, he turns to locate Keith.

The line of Keith’s spine is the first thing Shiro sees. After that, it’s the growing expanse of skin on display as Keith strides out of the little pool. Keith squats to rummage through his pile of armour for his underarmour and Shiro turns away, both to give Keith privacy while he dresses and to find something else that might hold his attention in the same way as the flex of Keith’s legs as he straightens. There’s not a lot on offer, but Shiro fixes his attention on a tree across the river, cataloguing the glittering emerald of its leaves and the way its branches drape down to the surface of the water, like hands reaching for a drink.

Shiro turns when Keith calls his name, in time to see Keith reach back over his shoulder and finish pulling up his zipper. “C’mon,” Keith says, pushing his hair back out of his face, “we should start heading back, you’re looking a little red across the shoulders.”

Shiro looks down at his own shoulders, seeing the dull red in his skin. A sunburn, he thinks, and then smiles. It’s been years since he’s had one. Space faring has left them all unusually pale, and Shiro has missed the deep gold of his summer tan.

Getting dressed is quick work, and soon enough, they are on their way again, pushing through thick undergrowth. They make it back to Red as the shadows are just starting to lengthen and Keith runs through pre-flight while Shiro stows their packs and comms ahead to the castleship to let their team know they’re on their way back.

Later, after mission debrief and delivering the plant to an excited Pidge, the team has dinner together as usual. There’s a loud discussion about movie nights that Allura puts a stop to by asking what popcorn is and Shiro can see no reason why anyone should be denied the very real pleasure of spending a night on the couch watching a bad movie in the company of friends.

Keith sits next to Shiro in the lounge. The movie on the screen holds no one’s attention for very long, and the lull of soft conversation doesn’t compete with the actors. Shiro tries to focus on the storyline and not the heat of Keith’s thigh pressed against his, but finds himself returning again and again to the sight of Keith, water beading on tanned skin, back to Shiro as he shimmied back into the flightsuit. The line of Keith’s spine, the toned muscles of his back, the trim waist; Shiro’s mouth waters. He swallows, stuffs a handful of something that approximates popcorn into his mouth, and goes back to staring intently at the movie.

No, he thinks when he finds himself, once again, straying to the rippling reflections of the water on Keith’s skin. This is ridiculous. Nothing special about seeing Keith in the nude, crowded dorms and crowded gyms lead to crowded showers. Shiro’s seen Keith in various states of undress for years, and he can and will keep it together, never mind that his brain seems overly fixated on the way Keith’s hair, damp from their swim, had curled faintly at the ends, lending Keith a softness his usual shag did not allow.

No matter how he tries to remain focused on the movie, Shiro finds his eyes drawn over and over again to the rhythm of Keith’s fingers on his own thigh, watching as Keith taps out the same four beats over and over again. Keith shifts. The beat falters, but resumes. Shiro rolls his shoulders, trying to ease some of the restless energy in his own body. All it does is make Shiro’s shoulder bump into Keith’s. Heat blooms at the contact point, and Shiro jerks himself away.

The tapping of Keith’s fingers stills, and Shiro feels the prickle of a flush down the back of his neck.

“I’m gonna turn in,” Keith says, and pushes himself to his feet. The rest of the paladins mutter good nights and see you in the mornings, and Keith takes his leave. Shiro works very hard to not watch him go, nailing his gaze to the middle of the movie screen and seeing none of what is happening on it.

He makes it five minutes before the twitch in his thighs turns into a bounce in his knee and then Pidge looks up at him from the floor, something knowing in her gaze. Shiro can feel himself colouring, and he stands, abrupt.

“Bed time,” he says, a little more sternly than he means, and then turns on his heel, and walks out.

The restlessness in Shiro’s veins becomes an itch under his skin on the way to his quarters. He can feel it climbing his spine, pooling heavy in his gut, prickling in the palm of his flesh hand and tingling in the seam between prosthetic and skin on his other arm. He clenches his hand, feeling his nails dig into his palm, and speeds up from a stroll to a brisk walk. At this rate, he knows he’ll be tossing and turning for hours. Maybe if he goes down to the gym and runs flat out for as long as he can, he’ll burn through whatever this is in his blood.

Shiro runs into Keith almost all the way back to the corridor they share, because Keith is coming back from his room. He’s already changed into gym gear, hair pulled up into a knot on the top of his head, strands escaping into a mess around his face. Shiro manages to keep them both from tumbling to the floor by some amount of grace he wasn’t sure he possessed.

He steadies Keith, hands wrapped around Keith’s upper arms. The restlessness eases minutely with the contact, but returns when Shiro steps back. “Thought you were going to bed?”

“Can’t sleep,” Keith answers, with a shrug. “Feels like I’ve been cooped up for days.”

“You too, eh?” Shiro says, then has a thought. “Gimme a minute? I’ll join you.”

“Oh,” Keith says, brightening, “sure.”

Shiro makes quick work of shedding what passes for his casual wear and tugs on a pair of shorts, grabs his running shoes and pulls on a soft t-shirt. On the hook by the door hangs his hoodie, and he stuffs his arms through its sleeves as he’s stepping back out into the corridor.

Keith is waiting where their hall joins the one Lance and Hunk share, leaning against a bulkhead, inspecting his nails. He looks up when Shiro’s door slides shut. When Shiro comes up beside him, Keith bumps their shoulders together and then falls in step beside him.

“I can’t seem to settle, like, at all.” Keith keeps pace with Shiro as they skirt the lounge and head for the gym. The movie is still playing, and they hear Allura’s laugh just before they get on the lift to one of the lower decks.

“Me neither,” Shiro agrees, after punching in the floor code, “haven’t really been able to since the swim this afternoon.”

“Do you think there was something in the water?” Keith asks, following Shiro into the gym, before breaking off for the mat next to the heavy bag. Shiro follows him, preferring to do his warm up stretching with company.

“Was safe to swim in, wasn’t it?” Shiro says, balancing on one foot to pull his other foot up and back, stretching out his quad.

“I guess so,” Keith agrees, voice muffled as he bends at the waist to touch his toes.

Shiro goes through his usual routine, while Keith goes through his, and Shiro manages, quite well, he thinks, not to ogle Keith while he’s stretching. It’s a challenge, what with Keith being a lot more flexible than Shiro remembered, or maybe he’s just never paid attention properly before?

“If it’s still a problem in the morning, we’ll go see Coran,” Shiro says, bouncing on the balls of his feet. Keith grunts in agreement from where he’s pretzled on the floor. Shiro’s not quite warm enough yet to properly run, so he sinks into a lunge, and then another one on the other side.

Shiro comes up out of the lunges and does ten jumping jacks, then another ten, and then finally, five more, because now Keith is watching him, one eyebrow raised in amusement. Normally, Shiro would have gone to get the jump rope, but he’s having trouble getting up the initiative to get further than a couple of arm lengths out of reach of Keith.

“You’re the only person who does jumping jacks with perfect form,” Keith says, getting to his feet and going to the other side of the bag to rummage through the cubby where he keeps his equipment. Shiro knows he should go run now, while he’s warm, while his blood is liquid, but he can’t seem to tear his eyes away from watching Keith wrap his hands.

Keith is meticulous about it, careful with the tape, and focused entirely on the task in front of him. Shiro knows he’s staring, but it doesn’t seem to matter. Eventually, Keith must feel the weight of Shiro’s gaze, because he looks up.

“Aren’t you supposed to be running?” Keith asks.

“What if I am?” Shiro replies. Keith’s eyebrow lifts again.

“What’s gotten into you?” Keith wonders.

Shiro shrugs. “Dunno.”

“Go do your miles, we can spar when you’re done,” Keith says, and then he’s pulling his gloves on with his teeth and Shiro has to look away.

Shiro makes himself walk over to the running booth, makes himself input his preferred course and fishes his earplugs out of his pocket. He doesn’t run with music, but Keith’s bag rhythm will mess with Shiro’s own, so he prefers the deadened silence.

The pace he’s set himself is punishing, but Shiro finds reserves of energy to spare as he runs through the pseudo-desert trail that the program has rendered in front of him. The last mile comes up quicker than he was expecting and then, all of a sudden, he’s through his cool down and stepping back out of the booth.

The towel that comes sailing towards him only misses his face by inches. Shiro snatches it out of the air, and then pulls out his earplugs, dropping them back into his pocket.

“Good run?” Keith asks, and Shiro nods. “Don’t know how you do that for fun,” Keith remarks, lifting the hem of his shirt to wipe off his forehead. There’s no artifice to the movement, Shiro knows, it’s not like Keith is trying to be appealing, this is just who he is, and frankly, Shiro should know better than to let his gaze linger on the flash of Keith’s skin. It’s not like Shiro didn’t know Keith was all wiry muscle, but for some reason, it’s different now.

Shiro covers his distraction by rubbing his towel through his hair. “You still up for a spar?” he asks, and he knows he’s not imagining the way Keith’s eyes light up at the suggestion.  

“You know it,” Keith tosses over his shoulder as he walks towards the big open floor space at the centre of the room.

The spar begins as they usually do, with both of them dancing in and out of reach, gauging the other’s reactions, testing limits and seeing how close they can get in before the other reacts.

Keith, like usual, is the first one to give in, and throws a meaningful punch that Shiro ducks easily, coming up with an uppercut aimed at the point of Keith’s chin. Keith jumps back, turns and comes back in swinging.

They trade blows back and forth. In the part of Shiro’s mind that is not focused on their fight, he admires Keith’s form - the efficiency of his movement, the way he uses his whole body and the way he is unafraid of getting in close to get a hit, even if it means Shiro can reach him. Shiro’s starting to pick apart Keith’s strategy of dancing in and out of reach when Keith lands a lucky shot to Shiro’s ribs. The glancing blow smarts, and Shiro grits his teeth.

Shiro goes on the offensive, pushing Keith back to the edge of the mat, eventually sweeping Keith’s feet out of from under him and sending the smaller man sprawling. Shiro steps back to wait, while Keith gets back to his feet.

Once he’s standing again, Keith bares his teeth in a grin. “That all you got?”

“You think you can handle this?” Shiro asks, stepping forward and then dropping his shoulder, turning in to feint and then throwing a smooth left cross that Keith blocks easily. Shiro steps into his follow-through and reaches for Keith’s shoulder. Keith ducks, and goes for Shiro’s middle.

Even pulled, the body shots sting, but Keith’s come in close enough that Shiro can get both arms around him, and so he does. Keith squirms, does something with one leg that Shiro doesn’t see and suddenly, Shiro’s flat on his back, Keith straddling him, knees tight against Shiro’s sides.

“Yield,” Keith says, leaning over Shiro to wrap his hands around Shiro’s wrists and pin him flat to the mat.

Keith holds his position, and Shiro lets him. Shiro’s eyes track a bead of sweat that slides along Keith’s hairline. Heat blooms along all the places where they are connected and Shiro swallows. He holds himself still, and Keith does the same. Shiro isn’t even sure either of them are breathing.

For a long moment, neither of them says anything. Then, Keith rocks back, as if he’s going to get up, but all it does is slide their hips together and Shiro can’t help the punched out gasp at the press of Keith’s ass against the line of his half-hard cock.

Keith freezes. Colour bleeds into his cheeks, the flush making the sunset of his eyes a deeper violet. Shiro watches him swallow, watches the bob of his Adam’s apple, thinks about the taste of the skin under the line of Keith’s jaw.

After what seems like a small eternity, Keith springs to his feet, and stumbles back several steps, nearly tripping off the edge of the mat. Shiro gets up more slowly.

“I’m sorry,” Shiro says, rubbing at the back of his neck. “That was–it’s not–ah, what I mean–”

Keith’s on him before he can blink. The kiss is a wet hot slide of lips and the near clack of teeth. Keith makes a breathy noise of need when Shiro’s hand comes up to sink into the fine hairs at the base of Keith’s skull. Shiro tightens his grip, just to hear Keith whine in the back of his throat. Keith’s own hands slide under the back of Shiro’s shirt, fingers meeting at the base of Shiro’s spine.

Shiro steps forward, pushing Keith back towards the wall of the gym. He hikes Keith up, slots his thigh in between Keith’s and lets Keith rut against him. Each time their hips come together, Shiro tries to swallow down the noise that wants to climb up his throat, and each time, it gets harder.

“Shiro,” Keith husks, pulling away from the kiss to drop his head back against the wall. Shiro takes advantage of Keith’s bared throat and finds the sensitive spot just behind Keith’s ear. The bite of teeth under Shiro’s jaw makes him shudder, and Keith soothes the bite with a hard press of his tongue.

“God,” Shiro groans, when Keith’s hands climb up his back, fingers splayed against Shiro’s shoulder blades, and blunt nails dug into the meat of muscle. It’s like Keith is trying to pull him closer, even though there’s no space between them. Shiro appreciates the feeling - it is extremely mutual.

Shiro leaves one of his hands in Keith’s hair and then other sweeps down Keith’s flank towards the hem of his shirt. Shiro shoves it up, pressing their bellies together as he does. Both of them gasp.

Shiro grabs hold of his shredded control, and sucks in a breath. Keith blinks up at him, wide-eyed, flush riding high on his cheeks. The hook behind Shiro’s navel is insistent, and Shiro can feel that Keith is just as invested in this as he is, but he has to make sure, something about this whole day seems purpose-built to get them to this point. They’ve worked out together for years, why is today the day that a spar turns into groping each other against the wall?

“Keith, wait,” Shiro says, surprised at how rough his voice sounds.

“Shiro,” Keith says, and arches against Shiro, seeking the same kind of pressure Shiro wants. “It’s like,” Keith’s hands slide down Shiro’s spine to grip his hips, “something’s in my blood. I can’t stop,” Keith tugs Shiro closer. “It’s like I want to climb inside you,” Keith says, voice hot against Shiro’s ear.

“It’s crazy,” Shiro says, into Keith’s shoulder. “I want you,” Shiro says, “more than I’ve ever wanted anyone in my life.”

“Aw fuck,” Keith groans, reaching between them while continuing to rock against Shiro. Keith fumbles with the front of Shiro’s shorts, fingers brushing against Shiro’s cock, and each time, it makes the air punch out of Shiro’s lungs. Keith catches Shiro’s eye while he presses the heel of his hand deliberately against the outline of Shiro’s dick.

Shiro grits his teeth, not wanting to go off like some teenager in his pants. “Christ,” he swears, forced out between his teeth, as Keith grips him through the fabric. “Keith, I–”

“Yeah?” Keith asks, mouth turned up in a challenge. Shiro wants to kiss the curve of the grin off Keith’s face, but he settles instead for reaching into Keith’s shorts, groping blindly. Shiro closes his hand around Keith’s cock, feeling the velvet steel of it, hot and heavy in his hand, and Keith whines, arching closer.

The position is not as comfortable as Shiro would normally want, but he has Keith’s dick in his hand, and Keith has Shiro’s dick in his, and it’s all Shiro can do to hold himself up when he goes weak-kneed as Keith’s hand twists. Keith’s hips move in time with Shiro’s hand. Their wrists bump together.

Shiro grunts, opens his grip, and curls his hand around himself and Keith’s hand. Keith lets go as Shiro’s fingers tighten around them both. The first slide makes Keith moan, and drop his head back, baring his throat again. Shiro presses forward, keeping his hand moving between them, feeling the pool of electric heat at the base of his spine.

“Baby, baby, baby,” Shiro chants, while Keith writhes against him, swearing incoherently. Keith’s voice rises, then his whole body goes bowstring taut and he’s spilling over Shiro’s hand with sound like he’s been punched. Shiro follows him in another couple of newly slick pulls, mouth pressed hot against the skin of Keith’s neck.

Awareness returns in fits and starts. Shiro realises he’s still holding both of them, then he realises he’s collapsed against Keith, trapping him against the wall. Keith’s breathing like a winded racehorse, trembling all over, and still holding onto Shiro’s shoulders like a lifeline.

Shiro shifts, clearing his throat as he does. “You okay?” he asks, pulling back enough to look at Keith.

“Yeah,” Keith answers, still sounding wrecked. “You–that was–” Keith stops, takes a deep breath in, and lets it out in a ragged exhale.

“Are you sure? You’re shaking,” Shiro says, metal hand coming up to curve around Keith’s jaw.

“I am?” Keith looks down at himself, lifting his hands off Shiro’s shoulders. “Oh,” he says, as he stares at his trembling hands.

“Lemme just–” Shiro says, and moves to step back, uncurling his hand as he does. His fingers are sticky. “I’ll get a towel.”

Shiro tucks himself back into his shorts, and hunts up one of their discarded towels. He wipes off his fingers and then hands Keith the towel. Keith takes it, wipes his own hands, and then tosses the towel in the direction of the laundry bin. Shiro notices that Keith has pulled up his shorts again.

“We can–”

“I think–”

Shiro demurs, but Keith shakes his head. “You first,” he says, still leaning against the wall where Shiro put him.

Where Shiro put him.

The thought staggers Shiro. He and Keith–they–that just happened. Something molten eddies in Shiro’s gut, pooling at the base of his spine and tingling in his fingers and toes. Shiro’s mouth waters. He swallows. “I should go.” The words are forced out, and Shiro hates every syllable, but they are words he has to say. “This shouldn’t–”

Keith’s hand snaps out, snagging Shiro’s fingers. “Don’t,” he says, and Shiro stops, caught in Keith’s gaze. “I wanted this,” Keith says. Shiro’s focus narrows to the dart of Keith’s tongue between his lips. “I still want you, I don’t know what’s happening, but Shiro, it’s like I can’t get enough of you.” Keith licks his lips, and heat rekindles in Shiro’s gut.

“Okay,” Shiro says, “okay. This is kind of crazy, right? We–I just–” Shiro shrugs, helpless.

“Stop thinking so much,” Keith admonishes. “I want you, you want me, why are you making it complicated?”

“Because it is complicated.” The breath goes out of the space between them, and Keith lets Shiro’s hand drop. The Grand Canyon is a mild slope compared to the sheer abyss that threatens to emerge at Shiro’s feet.

Keith crosses one arm across his chest, holding onto his other arm. “Did you not want this before today?” Shiro lets the question hang between them for too long, even though the answer is the most uncomplicated word. Something shutters in Keith’s eyes, and Shiro’s stomach tightens. He can’t allow this.

“No!” Shiro blurts out, and now Keith’s eyes widen, the flash of hurt vivid on his face. “I mean, yes, I wanted you, of course I wanted you. How could I not? You’re beautiful.”

“Then,” Keith asks, cautious but determined, “how is it complicated?”

“I–”  

“‘Shut up, Shiro,” Keith says, and grabs Shiro’s hand again. “You talk too much.” Keith’s voice has gone to embers and smoke. Heat blooms again in Shiro’s gut. He had thought that the initial rush was insistent, but this is not at all like the last time. Urgency sings in his blood. Keith’s eyes are dark, pupils blown wide, and Shiro wants to tip in and drown, falling headfirst into the dark star of Keith’s gaze.

This is insane, Shiro thinks, but he’s closing the distance between them, hand coming up to hold the side of Keith’s face. Keith’s eyes flutter shut, and he tilts his head up. Shiro shivers, the warmth of Keith’s skin bleeding through into Shiro’s metal palm. They meet in the middle, brief and incandescent. Shiro’s stomach swoops, and then Keith is moving, hauling Shiro after him out of gym and into the corridor.

Shiro’s quarters are closest so they make for his room. They’re barely inside the door before Keith is pulling Shiro’s shirt up and over his head. Shiro makes quick work of Keith’s, taking the hair elastic holding Keith’s hair up with the neck of Keith’s shirt. Keith shakes his head, making his hair fall into his face.

They’re a breath apart, Shiro pressing Keith back into the closed door. There’s a second of hesitation before Keith’s mouth curves, sly and impatient and then he’s pushing Shiro back towards Shiro’s bunk. Keith tumbles Shiro down onto his back, and chases him down. Shiro welcomes the bite of Keith’s kiss, teeth sharper than they ought to be, but there’s no space in Shiro’s head for anything more than the press of Keith’s skin against his and the wet hot drag of Keith’s tongue as he slides down Shiro’s body.

Keith looks up when he gets to the elastic waist of Shiro’s shorts, eyebrow raised. A beat passes between them, broken only by Shiro’s ragged inhale when Keith takes the hem of fabric in his teeth and pulls them down. Shiro shifts to help, lifting his ass and pushing at the fabric gathering at the tops of his thighs. Keith ignores that in favour of licking a long stripe up Shiro’s cock, already hard and flushed.

Shiro moans, pushing the back of his head into his pillow, flesh arm coming up to cover his eyes.

Keith swallows him whole, and Shiro bites down, hard, on his own knuckles to hold back the desperate whine he can’t quite manage to contain. He refuses to look down at Keith, knowing that seeing him with his lips stretched around Shiro’s cock will be Shiro’s undoing. Keith’s mouth is searing hot, one of his hands tight around the base of Shiro’s dick and the other pressed hard into Shiro’s hip, to hold him steady.

It’s hard to discern the separate sensations of what is happening, because Shiro’s entire mind is consumed by the knowledge that it’s Keith hunched over him, in Shiro’s bed; Keith’s mouth, Keith’s hands, Keith, Keith, Keith. Shiro arches, back bowing, toes curling, and Keith does something that sends white hot lightning straight into the pleasure centre of Shiro’s brain.

Shiro opens his eyes to find Keith grinning at him, licking his lips. “Did I–?” Shiro asks, and Keith shakes his head. “Oh,” Shiro says, breathless. He takes stock. His entire body is buzzing, nerves alight. The muscles in his gut jump, he can feel the way his toes are curled into the carpet where his feet rest on the floor.

“Do you want to?” Keith asks, squeezing his hand and then jacking Shiro slowly. Shiro grits his teeth, hissing out a breath.

“What about you?” Shiro asks, enunciating carefully. It feels like he’s drunk on some kind of potent liquor. Maybe he’s just drunk on Keith. Shiro doesn’t know, and he isn’t going to do any deep thinking about it, right now. Not while Keith holds all the important things in his hands.

“I’m good,” Keith says, and Shiro follows his gaze. Keith holds himself in his other hand. Shiro can see the perfect drip of precome beading on the tip of Keith’s dick, so flushed it’s almost purple.

“I want–” Shiro swallows. He wants Keith’s cock in his mouth, wants it so bad, he thinks he might already be able to taste it - the musk and silk of it, the weight of it, heavy in his mouth.

“What do you want, Shiro?” Keith asks, his voice like gravel. Shiro aches, he wants to hear his name like that, like it’s the lifeline Keith’s hanging onto, shaped by lips flushed red from sucking cock. He wants Keith like this always; eyes bright with the remnants of something that might’ve been tears.

“I want to suck you off,’ Shiro says, and Keith rewards him with a long slide from root to tip. Shiro’s mouth drops open on a ragged groan. “I want to lay you out, flat on your back, I want to watch you fall apart on my hand,” Shiro says, each word pulled out of him with the movement of Keith’s hand. “I want– ah , Keith, please,” Shiro begs.

Keith doesn’t need to be told another time.

Shiro arches off the bed when he comes, hands coming to rest in Keith’s hair. He falls back onto his pillow. Keith rests his head against Shiro’s thigh. Shiro is the one shaking now. He lifts a hand to sweep his hair off his face, and his fingers tremble in the air in front of his face. “God,” he says, with a sigh.

“Just Keith today,” Keith says from somewhere below Shiro’s navel. The bark of his own laughter startles Shiro and it makes Keith laugh too, the sound warm and rich.

“Get up here,” Shiro says, reaching for Keith.

It’s a quick thing to bring Keith over the edge too, but Shiro relishes the way Keith goes boneless against him, the way his eyes flare wide and dark. At the apex, Keith bites into Shiro’s shoulder.

After, they lie side by side in Shiro’s bed, pressed together from shoulder to knee. Sweat dries into a chill on Shiro’s skin. Keith’s a warm weight beside him. He’d stripped out of his shorts when he’d climbed up onto the bed, and Shiro’s own shorts are still twisted around his knees. It’s warm in his room and smells like musk and sweat. Shiro inhales, long and slow. The exhalation is shaky, even now.

“You okay?” Keith asks, in a mirror of their first encounter.

Shiro turns his head so he can see Keith. The blue glow of the trim lights in Shiro’s quarters limns Keith’s profile. “Yeah,” Shiro says, “you?”

Keith pauses before answering. His brow furrows, then relaxes, and his mouth curves up in a soft smile. “Yeah, I’m okay.”

“I never thought–” Shiro starts but stops when Keith rolls onto his shoulder, facing Shiro.

“You never thought what?” Keith prompts, when Shiro doesn’t immediately continue speaking. Shiro takes a moment to formulate his answer, contenting himself to trace the sweep of Keith’s fringe across his forehead and then down along the side of his face, fingertips skating along the edge of Keith’s jaw.

“I never thought I’d ever get here,” Shiro says, and Keith frowns. Shiro hurries to reassure him, “no, like, I never thought we’d end up here, in my bed, together.”

“Guess all it took was stripping in front of you to go for a swim in an alien river,” Keith teases, soft and fond.

“Guess so,” Shiro agrees, and pushes forward, just enough to claim Keith’s lips again.  The kiss is a gentle thing, just the slide of their mouths together, but heat blooms again in Shiro’s blood. He pulls back to look at Keith. Keith’s eyes open slowly, dark and lovely. Keith’s hand rests, heavy on Shiro’s waist. Shiro feels the shudder go through Keith, watches the ends of his hair tremble with the force of it. Shiro feels the echo of the quake in the space between his own ribs.

There’s a soft knock on Shiro’s door.

“Shiro?” It’s Allura.

“Something I can do for you, princess?” Shiro asks. Beside him, Keith waits, tense and silent. They’re both naked. Shiro doesn’t think the princess would barge in, but he has misjudged her before, and this would be a rather awkward scene for her to walk in on. If she does decide to come in, there’ll be no hope of hiding what they’ve been doing - not that Shiro wants to hide, but he’s not about sharing details of his relationships with people who are not in them. He’s not sure how Keith would react either. He hopes she won’t come in.

“I was wondering if you’d seen Keith? I have some… news.” Shiro finds he can imagine Allura’s expression quite well during that significant pause. “It’s very important,” Allura continues, “that I speak to you both as soon as possible. I’ll be in the kitchen.”

Keith opens his mouth to speak but Shiro shakes his head, and Keith subsides. “Okay,” Shiro says, to Allura, “give me a couple of minutes and I’ll meet you there.”

Allura doesn’t say anything in response. Shiro waits a tense thirty seconds before sitting up. “Well,” he says, looking down at Keith, hair like spreading ink fanned out across Shiro’s pillow. “I guess I should find you and we should go to the kitchen.”

“I wonder what’s going on,” Keith says, propping himself up to sitting as well. He casts about, looking for his shorts.

Shiro leans forward, tugging his shorts down and off the rest of the way, and then shifting to standing. He can feel Keith’s eyes on him as he pads across to his closet, and he relishes the feeling of being wanted, it warms him down to his toes. It’s been a long time since someone has looked at him like that.

He smiles to himself in the mirror hanging on the back of the door and catches Keith watching him. Keith grins back. “You need clothes,” Shiro says, and Keith nods. “Whatever you think will fit.” Shiro reaches in to grab what he needs and then gestures behind him. “All yours,” he says.

While they dress, Shiro thinks about what Allura had said, thinks about what happened this evening, thinks about the taste of the water on his tongue. Could there have been something else at work here? Maybe. Shiro’s mouth twists. What if none of this was because of things they were really feeling? What if something they touched or drank or ate or interacted with changed them irrevocably? No, Shiro thinks, silencing his burgeoning doubts, if there was anything, all it was was the catalyst to a reaction that was already happening.

Shiro would be lying if he said he hadn’t noticed Keith before today. He likes to think of himself as a reasonably well-adjusted person, given his particular experiences, so he won’t lie to himself about that. He might lie about how long ago he noticed, because some things are better kept to yourself, but Shiro definitely wanted what happened today, and, he thinks, as he and Keith leave his room to find the corridor empty and quiet, he’s glad it happened.

“Shiro?” Keith asks, just before they arrive at the lift to take them up to the deck with the kitchen. In lieu of answering, Shiro takes Keith’s hand, laces their fingers together and squeezes. Keith squeezes back.

“Whatever it is,” Shiro says, “we’ll face it together.”

The lift doors sweep closed as Keith leans up to make sure Shiro knows he understands.

Allura’s in the kitchen when they arrive, but she’s not alone. Coran leans against the counter, hands shoved into the pockets of his pants.

“Shiro. Keith,” Allura says, gesturing to the table. “Please, sit.”

Neither of them take her up on her offer.

“What’s going on, Allura?” Keith asks, and Shiro can hear the rasp in his voice, knows why it’s there and hopes to god he doesn’t flush and give them away.

“It’s not serious,” she begins, placating, “the effects should clear up fairly quickly.” She’s hedging, trying to break whatever it is to them gently. Shiro knows she’s doing it because she thinks it will help, but it grates. He’s had a lifetime of people trying to break things gently to him.

“Just tell us,” Shiro insists, interrupting Allura’s next platitude. Allura blinks, brows drawing together and eyes serious. She stares Shiro down, and Shiro meets her gaze, steady and undaunted.

“While you were on the surface of Tyvi, did you drink the water?”

Shiro turns his head to look at Keith. Keith nods, minute but firm, so Shiro turns back to Allura. “Yes,” he says, pleased that he sounds just as relaxed about it as he meant to.

“Have you been feeling restless? Overheated?” Coran jumps in, talking over Allura, who frowns up at him.

“Yeah,” Keith says, voice still scratchy. “We went to the gym. Shiro went for a run, I went a couple of rounds with a heavy bag. I’m usually amped after a mission, I didn’t think anything of it.”

“Has anything else happened?” Coran’s question is innocuous, Shiro knows, just a question to gauge the progress of whatever it is they think Shiro and Keith have, but it still makes his hackles rise instinctively. Whatever else happened or will happen between him and Keith is their business, regardless of medical necessity.

“Just tell us what’s going on,” Keith says.

“There’s a water soluble compound that flourishes on the surface of the planet, it wasn’t picked up in the initial scans because Pidge didn’t know to look for it. The symptoms of ingestion include a rise in body temperature, feelings of restlessness and urgency, and increased levels of arousal.” Allura’s voice drifts down into a whisper by the end.

Shiro can feel the prickle of a flush crawling up the back of his neck. “What–” he starts, but his voice is strangled.

Keith picks up the thread, “Is there anything we can do?”

Allura shakes her head. “Just time,” she says, “the effects shouldn’t last for longer than a few hours though, so you should be back to your normal selves in the morning.” Coran moves forward to press his hand against her shoulder. “I’m so sorry,” she says, looking up them both, “I should have known better.”

“No, Allura,” Keith protests, and Shiro agrees, nodding in her direction. “This isn’t your fault.”

“It’s fine,” Shiro says, “sounds like we can just sleep it off.”  

There’s nothing much else to be said after that, so Shiro takes his leave and Keith follows him out. They head back to Shiro’s quarters by some unspoken agreement. The walk is silent, but not uncomfortable, and Shiro takes Keith’s hand again, when they get on the lift, keeping a hold of it until they reach Shiro’s door.

“You could stay,” Shiro offers, suddenly unsure if Keith will take him up on it.

“I wasn’t planning on going anywhere else,” Keith says, and pushes past Shiro into Shiro’s room. Keith flops down onto the bed, pillowing his head on his arms. He looks up at Shiro, standing stuck in the doorway. “You coming?”

“I need to say something,” Shiro says.

Keith sits up, legs crossed in front of him. “Okay.”

Shiro takes a deep breath. “I want you to know that I definitely was enthusiastic about everything that happened today and that I would like to keep doing it, and I don’t think that’s whatever was in the water talking, because I wanted to do this stuff before we went to the planet but I didn’t know if you wanted to, so I never asked, and I’m sorry if I pushed you into anything you felt uncomfortable with and I don’t want you to feel pressured into staying here with me, or doing anything else, or--mmph”

Keith tastes like Shiro’s toothpaste. “Shut up, Shiro,” Keith says, when he pulls away. “You talk too much.” Keith looks up at Shiro, who can do nothing but gape helplessly. “Alien sex bacteria or not, I wouldn’t have done anything with you that I wasn’t comfortable with. You didn’t push, you checked in constantly and I’d be lying if I said I hadn’t thought about this before today, too.”

“Oh,” Shiro says, struck dumb.

Keith’s hand is soft on Shiro’s cheek, and there’s nothing but his own blood rushing in his ears as Keith leans in. “I’d like to stay,” Keith says, words pressed against Shiro’s lips. “If you’ll have me.”

Shiro gathers Keith in close, hands splayed low on his back. “Of course,” he says, “for as long as you’ll have me.”