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“Are you sure you’re okay with this?” Gwaine asked, his voice a low hum by Arthur’s ear. The words were nearly lost beneath another loud moan from Merlin as Arthur thrust into him. His strokes were slow and languid for now, his hands on both of Merlin’s hips as the skinny boy braced himself on his hands and knees. Arthur used his grip to push and pull Merlin onto his cock, trying to keep from snapping his own hips like he was dying to.
“Yeah. Yeah—I think so,” Arthur mumbled. Gwaine cocked an eyebrow at the qualifier, but then shrugged, accepting Arthur’s first response. It was as good as he was bound to get.
Merlin was the one who had wheedled them both into this. Well, Gwaine had been more than willing from the get go. But Arthur had required some persuasion. Inviting Gwanie to their bed was nothing new by now, but usually his participation was limited. Arthur had one iron clad rule: no one else penetrated Merlin. That intimacy was his, and his alone.
That certainly didn’t hinder Gwaine’s enjoyment. One of his favorite things in life was sucking Merlin off while Arthur fucked him, watching him fall apart under the double onslaught. On rare occasion he even let Merlin fuck him, putting on quite a show while Arthur watched. Those nights were rarer, but no less thrilling for everyone.
This, however, they had never tried before. It wasn’t exactly off limits, not enumerated in the rules Arthur had laid down. Probably because it hadn’t even crossed his mind. Arthur didn’t bottom often; in fact, he could probably count the number of times on one hand. Not because he didn’t enjoy it, though it wasn’t his favorite. It was just that Merlin was usually happier with Arthur’s cock buried in his arse, and who was Arthur to deny him? Merlin’s new suggestion didn’t interfere with that, and in the face of his enthusiasm Arthur had little grounds for objection. It did sound intriguing, at the very least.
“Just relax,” Gwaine murmured, sliding his hands down Arthur’s sides like a horseman calming a jittery mount. He let them come to rest over the swell of Arthur’s arse, gently massaging and letting his fingers slip further and further in between. Arthur tried to stay as still as possible, fucking into Merlin with a minimum of movement.
Gwaine lowered himself down onto the bed, propping himself on his elbows behind Arthur. He replaced his gentling hands with soft lips and teasing flicks of tongue. Carefully, moving deliberately so Arthur could feel his intent, he parted Arthur’s cheeks with his hands, letting his tongue dip down into the cleft.
Arthur barely managed to bite back a groan. He felt Merlin clench tighter for a brief moment, responding to Arthur’s flare of arousal. Merlin turned his head, trying to see what was happening over his shoulder, but Arthur’s body blocked his view. He let out a huff of frustration before letting his head hang back between his shoulders, lolling with the sway of his body and the rhythm of his panting breaths.
Gwaine slid his tongue lower, pausing just short of the tight ring of Arthur’s entrance. Arthur heard him chuckle, felt it as a gust of air over that sensitive flesh. It set his whole body shivering.
He involuntarily thrust backwards toward the fleeting sensation, pulling Merlin’s hips with him. They almost overbalanced, but Gwaine caught Arthur’s waist with a steadying hand, pushing him back upright. Merlin almost giggled, until Arthur pulled him back sharply, displacing all other sounds with a sharp gasp.
Gwaine waited for Arthur to resume his composure, purposely letting the anticipation build as Arthur waited for the inevitable. Just when he was sure Arthur was about to start huffing with impatience, Gwaine flicked out his tongue, gliding over the hole in a succession of quick strokes that stole the air from Arthur’s lungs. It was too brief, not enough to let him adjust to the sensation before it disappeared again, leaving Arthur feeling unbalanced and dizzy.
“Gwaine,” he growled in warning when he could find his breath again. Arthur expected more laughter, more teasing, but instead, for perhaps the first time ever, Gwaine took the hint. His tongue stretched out over Arthur’s entrance in a long lazy stroke, like a cat cleaning its coat, thorough and firm. Arthur felt his muscles ripple, muscles he usually never even thought about, now the focus of all his awareness.
“Whatever you’re doing, Gwaine, trust me, he likes it,” Merlin said between pants, his head still hanging limp between his shoulders. He was right; Arthur’s cock was responding, filling more than he had thought possible, stretching Merlin even wider. Arthur felt lightheaded, like the last ounce of blood had left his brain to rush south. Merlin groaned in appreciation and continued to rock himself back and forth, taking over when Arthur lost the ability to function in the face of sensation overload.
Gwaine continued his ministrations, alternating short, teasing laps with longer strokes, swirling around and over his hole, but not yet dipping in. It was beginning to drive Arthur more than a little crazy. It felt good, surprisingly so, but even though just a few minutes ago it had felt like too much, now it was no longer enough.
He tried to push himself backwards, to force Gwaine’s tongue inside, where he wanted it. Merlin’s hips followed him back, grinding down against his forward thrusts as Gwaine licked and teased, making Arthur squirm between them.
Arthur was close to complaining again, close to calling the whole thing off and giving Gwaine a thorough beating if he didn’t just get on with it, when finally Gwaine’s tongue slipped inside. But it wasn’t the quick flick Arthur was expecting; it was a hard thrust, opening Arthur wide. Arthur couldn’t hold back a cry, trying to buck his hips into the sensation and away from it at the same time. Merlin’s hips trapped him from retreating far, propelling him backwards and farther onto Gwaine’s waiting tongue.
Arthur vaguely heard Merlin moaning and muttering a string of filthy curses in the background, but his mind could barely process it. Gwaine was opening him up, sliding his wet tongue in and out in an unsteady rhythm, keeping Arthur off guard. Gwaine’s fingers came up to join in, sliding over the sensitive skin behind his balls before slipping in to join his tongue, one at a time. That pressure felt firmer, more satisfying, less ticklish and fleeting. Arthur tried to hold back any pathetic whimpers, but he sighed in relief when Gwaine pulled his mouth away and finally pushed those fingers deeper, giving him the solid pressure he didn’t realize he’d been craving.
Gwaine was quick after that, no longer lingering over each motion. He slid his fingers in and out with precise purpose, spreading them apart in a scissoring motion that burned briefly but quickly gave way to a greedy hunger for more. Arthur barely even noticed when Gwaine was up to three fingers, sliding in and out with ease.
He did notice, however, when that delicious fullness suddenly disappeared. Arthur’s motions ceased, earning him a disgruntled whimper from Merlin. Arthur turned to look over his shoulder, ready to curse Gwaine out. But Gwaine was right behind him, his chest pushed flush against Arthur’s back, one hand wrapping around the younger man’s chest to hold him steady.
Before Arthur could even react, he felt the blunt head of Gwaine’s cock against him, pushing past the first ring of tight muscle with ease. Arthur gasped, fighting his instincts to clamp down as Gwaine slid further inside, seating his full length with several fluid thrusts. Gwaine slid his free hand down Merlin’s back, silently calling him to still for a moment as Arthur adjusted to the double sensation.
Merlin looked back over his shoulder, his breath hitching at the sight of the two of them. Gwaine’s face was buried in the crook of Arthur’s neck, offering him wordless reassurances as Arthur tried to remember how to breath. Merlin didn’t think he had ever seen anything more beautiful, or arousing. They were very rarely intimate like this when the three of them were together, instead both focusing on Merlin. But they looked good together, both strong and rugged, Gwaine’s brown curls falling across Arthur’s golden skin. Merlin’s cock twitched with renewed enthusiasm.
Arthur felt Merlin pulsing around him, and it brought him back from his mindless fog. He slowly opened his eyes, though he couldn’t remember letting them shut. Merlin was still looking back at him, as if waiting for reassurance that Arthur was alright. Arthur wasn’t quite sure if he was; he felt like he was about to burst at the seams, surrounded and engulfed by heat on every side. It was hard to process everything at once, his body parts feeling disconnected, like they belonged to two different people.
Gwaine watched Arthur’s face closely, waiting for a silent signal. Arthur looked overwhelmed, but not panicky or in pain. His face was slowly beginning to smooth out, losing its look of tense surprise. Gwaine took that as his opening to slowly move his hips; not daring to thrust yet, just gently grinding himself against Arthur, reminding him of the rigid, eager flesh buried inside of him.
That seemed to jerk Arthur back to awareness, a low moan falling from his slack lips. Gwaine took this as a positive sign, and tried pulling out just the slightest bit before pushing back in. Arthur pushed back against him, seating Gwaine even deeper.
Gwaine deemed the kid ready. He started a slow rhythm, pulling out and pushing back in with shallow thrusts. Gwaine reached forward past Arthur, resting his hands on Merlin’s hips. Merlin grunted as Gwaine pulled him backwards, sealing him tight against Arthur’s pelvis. Together they rocked back and forth, Arthur letting himself be maneuvered between them like a boneless ragdoll. Gwaine pulled them all backwards, impaling Merlin further on Arthur at the same time as he seated himself fully, making the three of them grunt in tandem. When Gwaine pushed his hips forward it thrust Arthur against Merlin, driving him deeper.
It was slow and deep and satisfying, but they couldn’t last at that pace forever. Gwaine gave Arthur a few moment to adjust, before calling him back to his duty.
“Arthur,” he whispered, close by his ear, “you have to help me. It’s time to give Merlin what he needs. He’s been so patient.”
Merlin grunted his agreement, pushing back against Arthur to accent his point. For Merlin it was beginning to feel like slow torture, a constant deep pressure, but not quite fast enough, not enough friction to really get him off. He had been patient, wanting to try something new, wanting this to be good for Arthur, but if he didn’t come soon he was going to scream.
The haze of Arthur’s eyes cleared a bit, called back to his body by that gentle voice. Gwaine took Arthur’s hands and replaced his own on Merlin’s hips, putting Arthur back in control.
Arthur took the hint, snapping his hips forward with renewed force. Gwaine moved with his rhythm, letting Arthur push and pull himself between the two of them, forward into Merlin and then back onto Gwaine, a steady rolling of his hips like an ocean wave.
“Good, Arthur, now harder. Fuck him faster, he’s begging for it,” Gwaine whispered seductively, and Arthur obeyed, like a soldier following orders. He pushed into Merlin faster, grinding his hips forward with each jerking motion, to the rhythmic sounds of panting breaths and slapping flesh. Gwaine continued to whisper encouragements and suggestions, punctuated by Merlin’s moans of approval.
Gwaine sped up his own rhythm, giving Arthur no choice but to follow suit. Gwaine could tell they were all close now. They were like a line of precariously aligned dominoes; once one tipped over the others would be swept along.
“Touch him, Arthur, he’s been waiting for it all night,” Gwaine suggested.
“Oh, God, yes,” Merlin agreed, nodding his head vigorously. That sounded just perfect right about then.
Arthur reached forward, stroking Merlin’s cock with one hand while the other remained on his hip, holding him steady as the combined force of Gwaine and Arthur pushed forward into him. Arthur tugged, once, twice, and once more, before Merlin came. His voice was nothing but a choked rush of air, sounding almost like a sob of relief as finally all the built up pressure dissolved into a blinding arc of pleasure, his entire body arching into it.
Gwaine was right; Arthur couldn’t last long against the onslaught of Merlin clutching tightly around him while Gwaine continued to drive into him from behind. Arthur thrust into Merlin once more before losing it. Merlin was already sliding forward and away by the time Arthur had barely finished, collapsing in an exhausted heap on the bed.
Arthur lost his balance as Merlin fell away, falling forward onto his hands and knees. Gwaine’s hands flew to his hips, pulling him backward on reflex, burying himself even deeper. He groaned, though Arthur seemed too incoherent to even react. His shoulders and neck were flushed and he was panting, still recovering from his own release. Gwaine didn’t want to push him too hard when he was already so wrecked, so he concentrated on pushing himself over the edge as quickly as possible.
It wasn’t hard when he looked down and saw Merlin, now stretched out on his back, lean up to kiss Arthur, long and slow, both of them blissed out and lazy. It was the kind of tender moment Gwaine felt privileged to witness, something just between them, a gentle side that others rarely saw.
It only took a few more strokes, watching as Merlin playfully sucked on Arthur’s neck, making him squirm in an unintentionally delicious way. Gwaine felt his orgasm rip through him like an unexpected bolt of lightning; the thunder had been building for some time, but that flash still felt sudden and blinding when it finally appeared.
He pulled out carefully, feeling Arthur wince slightly, and collapsed beside them, careful not to crush any of Merlin’s scrawny limbs.
“So,” Merlin said, pausing from planting sloppy kisses on any part of Arthur he could reach. One of his arms was thrown across Arthur, reaching over to run lazy patterns down Gwaine’s chest. Arthur looked to be falling asleep already, pillowed between their dual warmth. “I think we can all agree that I am a genius.”
“Yes, I’m sure the Nobel committee will be calling you any day now,” Arthur mumbled, his face buried against Merlin’s shoulder. His intended sarcasm was undercut by his exhaustion.
Merlin and Gwaine looked at each other, managing to hold their composure for almost half a second before breaking down in to fits of giggles.
“I hate you both,” Arthur mumbled, grabbing a pillow and burying his head beneath it. It was mostly to hide the blush rising on his cheeks, though they probably weren’t fooled. He hadn’t exactly disagreed, after all. Arthur let himself drift off into an exhausted sleep, calmed by the lullaby of breathless laughter and happy murmurs from the two people he cared for most.