Title:

Title: Theory of Relativity

Author: Mice

Category: Stargate: Atlantis, Zelenka/Beckett/McKay

Warnings: slash, humor

Spoilers: none

Rating: NC17

Summary: Zelenka tests a little theory.

Archive: If it's on your list, you can archive it. If it isn't and you'd like it, just let me know where you're putting it.

Feedback: Feed me, Seymour.

Website: Mice's Hole in the Wall https://www.squidge.org/mice

Mirror: http://mice.inkpress.org

Disclaimer: Not mine. They belong to many other people. But if they were mine, they'd be having very interesting adventures.

Author's Notes: Written for my beloved beta Zortified, who said, "Well if you're gonna *insist*. ;-) Carson/Radek established, with an optional Rodney-threesome (either first time or established three). Um. No clue on any sort of plot. Happy ending. Silliness maybe? Reduce one of them to helpless laughter." You got everything but the helpless laughter, my dear. Beta by Pas, who drooled on her keyboard a lot.

~~~

Radek made a warm, content sound, snuggling closer to his sleeping lover. Carson shifted slightly, mumbling under his breath. It had been going on for a month or so now and Radek was no longer uncomfortable with it, though he'd been surprised at first.

"Rodney..." It was the name Carson whispered in the night, when he wasn't speaking Radek's. It was voiced with undertones of longing and desire. He saw the way Carson looked at McKay, when he thought no one watched. He'd said nothing, because Carson had never once mentioned his interest when he was awake.

Slipping one arm around Carson's chest, he laid his head on the broad, comfortable shoulder. From this angle Radek could see his lover's profile clearly even without his glasses. He studied Carson carefully, wondering if it would be right to talk to Rodney. Despite the fact they crossed verbal swords regularly, he genuinely liked the man. Ego notwithstanding, he had a good heart. Well hidden to be sure, but there.

The question Radek had to ask himself was: would doing this be worth the risk? He cared for Carson. Loved him, perhaps. They'd never said the words to each other, but he thought Carson felt the same. There was a look in his eyes that betrayed something deep when they were together. They'd been discussing living together. Yet Carson wanted Rodney. Would he leave if he had the man?

Hypothesis: in the night, Carson spoke Rodney's name, but he also whispered Radek's. Carson had broached the idea of sharing quarters last week. Given this evidence, it stood to reason that Carson was not interested in leaving. If anything, it suggested that Carson was perhaps slightly less straitlaced than Radek had originally assumed when they found themselves in bed together.

The next question Radek asked himself was if he was interested in Rodney. This was, as the Americans often said, a no-brainer. Rodney fascinated him. He wasn't as handsome as Carson but there was a certain appeal, if one liked tall, arrogant men with intense blue eyes and a sense of humor that threatened devastation.

He could pass on the arrogant, but Radek suspected that Rodney would be considerably less so if held between two lovers intent on turning his grey matter to gelatin. He found the idea of an inarticulate Rodney McKay quite attractive, actually. The chance to make the man speechless would be exceedingly difficult to pass up.

Radek was quite certain McKay was interested in men. Specifically, he was interested in Carson. Radek had seen him... appreciating Carson on many occasions since they'd met in Antarctica. Rodney, however, was far more socially inept than most, and Radek had made his own advances to Carson before Rodney ever got up the courage to say anything to the good doctor. It was McKay's loss, and Radek didn't regret that for a moment. Their quiet affair had been going on for seven months now, and both of them were happy in it.

He sighed and kissed Carson's rough, stubbled cheek. The risk analysis seemed plausible. Reasonable even. Carson would not leave. Rodney would most likely say yes. Radek would be most interested to see the results of his experiment.

It was time to test the theory -- tomorrow.

***

Rodney stared at him. "It is not so far-fetched," Radek said. Rodney said nothing, opting to continue staring. Yes, speechless. It was a good look on the man. Radek smiled. "I will let you contemplate this on your own. I should say I have not yet told Carson that I'm aware of his interest. I wish to keep it this way for the time being."

Rodney's mouth opened and closed. He looked very like a large carp. A carp that had, perhaps, been pole axed. Radek's smile broadened as he left Rodney at the breakfast table.

***

It was two hours before Rodney collared Radek in the lab. "You. My office. Now." He jerked a thumb over his shoulder toward the storage closet that served as Rodney's 'office', when he bothered to use one. Radek nodded and followed, and Rodney closed the door behind them. "You're not serious."

Radek sat on the desk. "Actually, I am most serious."

"You *can't* be serious!" Rodney insisted. "Why the hell would you want to let Carson be with me? I mean, don't get me wrong, I think it's a fabulous idea. Pure genius. Not on my level, of course, but very close--"

Radek held up a hand, putting a stop to the torrent. "Rodney, is this a yes or are you merely giving me an exceedingly over-complicated no?"

"Yes. And by that I mean, ah, yes." Rodney looked nervous, his shoulders twitching just slightly as he stood next to Radek. "But, um... can you give me a few details?"

Radek poked the bridge of his glasses with one finger, shoving them back up his nose. "I think perhaps you should meet us at my quarters after work tonight," he said.

"You're going to talk to Carson first, aren't you?" Rodney asked. "I mean, the whole rejection thing; I'm not so sure I could do that. Are you *sure* he's interested in me?"

"Trust me," Radek said, and grinned evilly.

Rodney paled. "The trust thing, not so good. How do I know you're not just messing with my head?"

Radek shook his head and crossed his arms over his chest. "If I were going to do that? I would be accusing you of mathematical errors in your unification theories. Since of course they do exist."

Rodney snorted and glared at him. "You know I'm close."

"Like trilobites and gigabytes are close." Radek snickered. "So you will join us tonight. Come over about eight."

Rodney nodded and blinked. "Eight. Right. Your place."

Just to mess with Rodney's mind further, he leaned in and placed a soft kiss on his lips. When Rodney gaped, Radek turned and left. Oh yes. The experiment was moving along most wonderfully. If Carson cooperated, the night might yet be truly memorable.

***

Rodney was sitting nervously in Radek's quarters when Carson arrived. Carson blinked, looked at Radek, looked back at Rodney and then smiled and said, "Is there some emergency, Rodney?"

"No, Carson," Radek told him. "He has come to visit for the evening." Radek touched his shoulder and Carson gave a quick glance to Rodney again as he was pulled into a hug. Carson's arms came up, awkward, and circled him.

"I thought we were keeping this to ourselves for a bit yet," Carson said quietly in his ear.

Radek took Carson's face between his hands and kissed him, soft and sensual. When he opened his eyes again, Carson's were closed, a look of surprised pleasure on his face. "I know what you want, Carson. If you wish, we are willing to give it to you."

Carson's eyes shot open, shocked, and he gasped. Radek smiled. Rodney shifted uncomfortably behind them.

"I... you... how..."

"Babbling really doesn't become you," Rodney said. Radek could hear him stand and move, then Rodney's voice was at his ear. "Are you sure?" It was soft, tentative -- perhaps even a little fearful.

Radek looked Carson in the eyes. "The decision is yours," he whispered.

The tension between them was almost liquid, thick as honey. They were still for a moment, all three of them, and then Carson reached out with one hand and touched Rodney's cheek, wonder on his face. "Yes," he whispered. "God, yes."

Rodney and Carson's first kiss was tentative, their second, electric. Radek was barely breathing, watching as they touched, bodies meeting gently then coming together with a passion that left him as stunned as they were. It was, quite possibly, the most erotic thing Radek had seen since... well, since the first time he'd seen Carson come.

Their arms were around each other, holding each other with a hint of desperation that left Radek hard and aching. He extended one hand, his fingers trailing down the back of Carson's neck, and Carson shuddered, gasping into Rodney's mouth. Rodney moaned and Carson echoed him, devouring each other. When Radek traced his lips along Rodney's ear, Rodney whimpered.

A moment later, Rodney broke the kiss and looked at him. Carson just stood there, eyes closed, panting in Rodney's arms. Rodney tilted his head to Radek and they kissed. Rodney's kiss was as devastating as his words so often were. Radek slid his arms around them and they both embraced him, Carson tasting his neck, Rodney still kissing him deep and wet and hard.

Strange, Radek thought, how one's perception of a man was relative to how one felt about him. He knew he would never feel the same about Rodney again. This passion, this depth, he'd never suspected it.

"Yes," Rodney whispered, his lips moving on Radek's. "Why?" There was longing in the question; confusion and desire in some alchemical blending and Rodney's blue eyes were bright with it all.

Radek looked at Rodney then turned to Carson, kissing him softly. Strangely, there was no element of possession in the kiss. He felt no urge to lay some exclusive claim on Carson. The fact they were here, were doing this -- Radek trusted it to turn out well. "For you," he said softly and kissed Carson again. "Because I know how you both have wanted this."

"How did you know?" Carson asked. There was something guarded in him, a hint of uneasiness. "I never said anything." He looked at Rodney. "I didn't."

Radek smiled. "Not while you were awake, but sometimes you have said Rodney's name in the night, as you also say mine." Rodney's eyes widened at that, and Carson seemed startled. "And I have seen you watching each other. It is not so great a secret as either of you have imagined."

He could feel Rodney's pulse quickening. "Did you know," Rodney asked softly, "that I was watching you too?"

"I had a theory," Radek said. He grinned and kissed Rodney again. He closed his eyes and fell into the heat of Rodney's mouth. Carson's warm breath caressed his neck as his lover kissed Rodney's throat. Hands moved on bodies and Radek lost track of who was touching whom. It didn't matter, really. It only served to prove his theory, after all.

Zelenka's Theory of Relativity: when one's lover mumbles one's name and the name of one's best friend in that particular tone of voice in the middle of the night, it is possible that a very successful threesome may be the result.

He had evidence. Nudity was the next step, of course. Expressing his proofs would be a pleasure.

Radek doubted there was a Nobel in it, but it seemed elegant. And at any rate, the experiment would need to be repeated any number of times, provided the first result was a success. He could live with that, quite happily.

There was a delightful symmetry to the sounds they all made. Soft moans and quiet sighs greeted the touch of fingers on flesh. Lips produced almost inaudible groans and the catch of breath. As shirts were slowly removed, the palms of hands joined the multilingual chorus. Radek thought perhaps they all spoke with the tongues of men and of angels. Carson's tongue was angelic -- he'd had proof of that for months now. Rodney's -- well, Rodney kissed like a demon afire. He traced blazing trails on Radek's shoulder with lips and tongue and his fingers moved on Radek's back.

It was with some surprise that he found himself between Rodney and Carson. He'd rather thought Rodney might end up in the middle instead, but he had no desire to argue the point.

As the moments went by with almost event horizon slowness, Radek began to be able to tell the touch of Carson's hands from Rodney's. There was a delicacy to Carson's touch, and Rodney's fingers were slightly calloused from all his work in the field. Rodney's hands were broad and strong. Carson's knew all the places that gave Radek the most pleasure.

He could live all night on the comparisons. Radek sighed happily, kissing one then the other, watching as they kissed each other over his shoulder. This, he thought, was the closest thing to bliss he could imagine. Well, for the moment. There were other things he wanted to try before the night was over that would provide even more pleasure.

Their bodies pressed against him, before and behind. Four arms encircled him, and his own held Rodney. Close like this, the man was more substantial, harder than Radek had suspected; the result of all he did in the field, of course. Carson was softer, but had an undeniably impressive presence. Radek sighed, held by the strength of both men, and Carson nibbled at the nape of his neck.

"Carson," Rodney whispered, and there was an ache in it that shot through Radek like a bullet. Yes, this was good, this was right. Rodney's desire for Carson matched his own and Radek was hard, his flesh pressed into Rodney's erect shaft. Carson moaned softly behind him, his own hardness burning into Radek's back.

"I want to see you together," Radek said softly, kissing Rodney then Carson. "Please. I can feel how much you want each other."

Rodney gasped and kissed Radek passionately. Carson groaned and thrust against Radek's back. "Oh, god, yes," he said, his voice rough with desire. Radek had always loved that sound in Carson's voice.

They shifted, dropping trousers and shorts, kicking shoes away, tossing socks in random directions as they moved toward the bedroom. Radek was uncertain as to the exact mechanics, but they made it to the bed without losing physical contact with each other. He wondered if he would ever be able to chart the vectors involved.

The bed at his knees distracted him as they settled, snuggling together. Carson and Rodney had locked eyes, drinking each other in, and Radek just watched, his hands stroking each of them gently, touching their sides, their backs. They paid him no attention, but he was pleased with what he saw.

Carson moved, and then he was on top of Rodney, kissing him madly. Their hands searched each other, exploring with trembling fingers. Radek held his breath with his watching. They were beautiful together. Their heat and passion left him shaking with desire. Rodney moaned, loud, as Carson kissed and sucked at his neck. His eyes were closed, head thrown back, and he pulled Carson closer as though to have a single molecule of air between them was too painful to contemplate.

Radek knew how it felt, for he had touched Carson like that as well. He would again and, perhaps, if he were fortunate, he would share that same want with Rodney. Like this, Rodney was handsome and incredibly desirable. This watching them swelled in his chest as though he might burst. It stirred Radek and he trembled as though each of his cells was vibrating, resonant with the depth of their voices.

To be witness to a moment like this, it was a thing of immense privilege. His heart tightened with how much they must have wanted each other, and he wondered why Carson had never said anything. Radek would ask, but later, in the rising light of dawn. He leaned down and kissed the back of Carson's neck, licking his way slowly down his lover's spine. Carson moaned and shuddered and Rodney gasped, "yes."

Radek nibbled his way up Carson's back again, fingers tracing the shape of muscles, the ridge of spine. As he reached the base of Carson's skull, he saw Rodney watching him, eyes dilated, panting. Softly, he leaned down and brushed his lips against Rodney's. They moaned together, quiet and needful as the length of Radek's body pressed against Carson's.

Rodney's hand found Radek's cheek and Rodney opened his mouth to him. Radek kissed, still soft but deep. The magnitude of what was happening between all of them was more than Radek would ever have thought possible. The heat they shared dug into him, burrowing into his marrow. Why had he never suspected this? He'd seen such longing between Carson and Rodney -- why had he never seen how Rodney wanted this as well?

Why had he never realized how he had wanted it too?

His hypothesis shifted. His theory had to answer for multivalent realities, for multiple layers of desire and the need that echoed between all three of them. Speechless lips were eloquent when they met, and Carson's warm breath was in his ear, tongue moving along the curve of it. Radek shivered at the tingle down his spine, hard and aching.

"Do you want Carson inside you?" Radek whispered, his lips still moving against Rodney's. Rodney shuddered and gasped, his hand tightening on Radek's jaw.

"Oh, god, yes." He was panting, his eyes half closed, blue like the depths of the sea. "Please."

Carson moaned in answer, his body moving under Radek's, hips thrusting slowly against Rodney. "I want you," Carson said, his voice leaving an ache in Radek's chest. Radek wanted to see them together, to watch Carson take Rodney, moving inside him slow and deep. He wanted to watch Rodney break under his lover, watch him gasping, chest heaving, coming.

He wanted to be inside Carson when it happened.

More technicalities. He found lube as his fingers traced Mandelbrot sets in the slick of sweat on Carson's shoulder. Radek watched as they moved together, eyes closed, kissing each other's faces. There was such strength and power in their movement, and he was glad to be a part of it. His fingers moved in curves and spirals along Carson's side to the arc of his ass. He covered the muscle with one palm, stroking slow and solid. Carson groaned softly and lifted himself away from Rodney's body.

One arm reached down and Carson slipped it under Rodney's knee, drawing his leg up, opening him. Rodney sighed, a pleased, sensual sound, his hands splaying on the bedspread. "Please, Carson," he whispered. He raised his other knee, bracing his foot on the bed. "Oh, god, I want you in me."

Rodney was hard and throbbing, leaking a bit as he panted. His body was flushed with his desire and Radek just looked, taking in Rodney's deep and obvious need. He was solid and well built, strong cock jutting from dark curls, his balls drawn up tight beneath it.

Carson made a quiet, strangled sound as he looked down at Rodney spread open before him. Radek slicked Carson's thick cock with slow strokes and Carson shuddered, eyes closing. "Feels so good," Carson said softly. "So good."

"You will feel so much better inside him," Radek whispered in his ear. He grinned when Carson shivered.

"You're the devil himself," Carson said, and kissed Radek's cheek. "Tempter."

Radek's grin broadened. "And who would not like a demon lover?" he asked, "or to be given such a temptation?" Leaning forward just a bit, he slipped one slicked finger into Rodney, who gasped and made a sound so filled with need that Radek almost came from it. "He's very tight," Radek said into Carson's ear. "I can imagine how you will feel in him."

"God damned tease," Rodney growled. "Get out of the way and let Carson fuck me." Radek slipped a second finger inside him instead, and Rodney whimpered. He watched as Carson's shaft leapt and Carson was panting with want, his hand kneading Rodney's thigh.

"Yes yes yes," Carson whispered. He took Radek's wrist and pulled him out of Rodney, then tugged Rodney's hips into his lap. Radek watched, breathless, as Carson entered Rodney slowly. Rodney groaned and begged for more, his eyes squeezed shut. After a moment neither spoke, just moaning and moving together as Carson thrust slowly deeper.

"Jezisi," Radek whispered. "Magnificent." And it was, truly. Both of them were flushed, glistening with sweat, moaning softly. Rodney's hands fisted in the bedspread as Carson moved inside him. Their movement grew easier, more fluid after a few long thrusts and Radek stroked himself as he watched them.

"Radek," Carson whispered, his voice strained. "Please, in me."

He knelt behind Carson, slipping into him easily, and Carson moaned and shuddered. He was hot and solid in Radek's arms, moving slowly, the sound of need and pleasure deep in his voice. It was almost too much to bear, being in Carson, feeling his lover moving under him as Carson thrust deeply into Rodney.

Rodney looked up at them, eyes half closed, pupils dilated. His head rolled to one side and he muttered, "God, so good..." Radek reached around Carson, taking Rodney's thick shaft in hand and squeezed. Rodney jerked, gasping. "More," he begged.

"Not so much," Radek panted. "You are using this on me when Carson's done with you." He grinned tightly, thrusting harder into Carson, who groaned and came under him. Rodney made an incredible sound, eyes closing, and grabbed Carson's shoulders.

Radek didn't stop thrusting, and Carson sank onto Rodney's body. Rodney lowered him gently, still panting, and cradled Carson in his arms. "God, Radek," Rodney said, "keep doing that. He's -- he's still hard. God, I need this."

Carson just made a low, content growling sound, hips still moving as Radek moved in him. He was so wonderfully tight. Radek wasn't sure where he ended and Carson began, and there was Rodney, looking into his eyes like he had just realized some great mystery. He couldn't look away -- Rodney's eyes were so dark, filled with something entirely different than Radek had ever seen in them before. And then Rodney reached up with one hand and tugged him down, kissing him, eyes closing. He moaned softly into Rodney's mouth, pumping into Carson, moving more quickly now, and part of him wished it were Rodney he was fucking.

But there would be time for that. Because Radek's theory had shifted again with the heat of Rodney's mouth and the way Rodney's tongue slipped against his as they held Carson between them. He was thinking in terms not of relativity now, but of unification. Radek Zelenka's Grand Unified Field Theory: When one was fucking one's lover and kissing one's best friend -- whom one's lover was fucking -- the permutations of relationship grew exponentially. Rodney's mouth held infinite possibility, and their three slick bodies moving together were far more sensual than only two men making love.

Union. That is what it was. Not just bodies moving. Not just friends suddenly discovering more. Radek pulled carefully out of Carson's body, wanting to come with Rodney pounding hard inside him. "Move," he said gently, tugging at Carson's shoulder.

Carson rolled to his side and looked up at Radek, still half hard. He smiled. "Thank you," he whispered, and kissed Radek's chest, which was all he could reach at the moment. He looked over at Rodney. "And you." Carson's eyes were heavily lidded but keen. "I want to see you both," he added.

"In a moment," Radek whispered, and kissed Carson's mouth gently. He looked at Rodney. "Come here."

Rodney moved and rose, taking Radek into his arms. They kissed, slow and deep, with a passion immense as waves in a storm. Radek twisted a little afterwards, turning his back to Rodney. "Like this," he said, one hand on Rodney's thigh, tugging him forward.

Carson pulled on Radek's arm and snuggled under him, chest to chest, mouth to mouth as Rodney pushed into him. Rodney was big, his shaft thick and moving hard inside him. Radek moaned into Carson's mouth, hands tightening on Carson's shoulders, and both of them held him tight. Rodney's arms were around his waist, hot breath in his ear.

"Oh fuck," Rodney moaned, moving faster.

"Yes, yes," Radek begged. "Harder, Rodney." His voice was muffled against Carson's lips, his hot, throbbing cock held tight in Carson's hand. "Is good; very, very good."

Rodney grunted, thrusting harder. "Never knew," Rodney gasped. "Damn, so hot." His fingers caressed Radek's stomach, carding through the hair there, reaching up to where Radek's body met Carson's.

With four hands on him and Rodney pounding into him, Radek came. Carson swallowed Radek's howl, pumping his cock, and Rodney shuddered, tightening his grip on Radek's body.

"Oh god, oh god--" Rodney's voice broke as he came and they both collapsed on Carson. Everything was still for long moments, the three of them gasping together, trying to catch their breath. Fingers moved slowly as they touched each other, trying to find their center again.

With a shift like the motion of tectonic plates, they slid out of the pile and lay side by side, Radek in the middle. Two mouths kissed his throat then two scratchy chins moved under his as he heard them kiss each other. He reached up carefully, running his fingers through their hair. "I want a kiss too," he said.

Carson chuckled quietly and then there were two mouths on his own. Radek sighed, content. He opened his eyes and looked over at his lover. Carson smiled down at him, a light in his eyes.

"Why did you never say anything about this?" Radek asked.

Carson's expression shifted, slightly uneasy. "I didn't want to hurt you," he said quietly. "Didn't want you to think I didn't want to be with you."

Radek nodded. It made sense. "I think I might have worried at first," he admitted. "But not after you asked me about living together." He heard Rodney sigh softly and turned to look at him. There was disappointment in Rodney's eyes. "There is nothing here to worry about, my friend," he said gently.

"I just... you two." Rodney looked away.

"And this is why you never said anything either?"

Rodney nodded. "When I realized the two of you were together, I really didn't think there was anything I could do. This--" he gestured, indicating the three of them together, "this never occurred to me." Rodney's body shifted, one leg slipping over Radek's thigh. Rodney put a hand on Radek's chest, still not looking him in the eye. "Radek, I..." He paused, taking a deep breath. "Can I stay the night?" he whispered.

Radek thought his heart might break at the loneliness in Rodney's voice. He pulled Rodney's head over, making the man look at him. "You can stay as long as you wish," Radek said.

Carson reached over him, taking Rodney's shoulder in one hand. "As long as you'd like," he echoed.

Rodney's eyes lit and he grinned.

Radek wondered how large a bed he would need for the three of them.

~~pau~~