Happy (only barely) early Halloween! Publishing this without a single bit of editing because I'm crazy busy and I promised superbored85 it would happen. Apologies for mistakes!

Merlin tossed his black cape over his shoulder, pulling on his boot to complete his costume. He snuck a look in the mirror, smiling goofily at the sight of Robin looking back at him. Unable to resist, he twirled a bit, grinning as his cape swirled about him. He was about to turn away when something in the reflection caught his eye, and he sighed.

"Arthur!" he shouted, marching over to the bed and picking up his boyfriend's cloak and crown, which he'd laid out for him earlier. "Why haven't you put your costume on yet? We're going to be late for Gwaine's party."

"Who says I'm not dressed?" Arthur's voice replied loftily. Merlin turned around, and felt his jaw drop.

The first thing he saw was the shirt. Thin white, and just a little too big, it hung artfully over Arthur's torso, opened to a low 'v' at the neck to show off his muscular chest. It hung low on his hips, leading down to black pants that fit just short of snugly, paired with boots that almost reached his knees. Dragging his eyes back up, Merlin noted the pirate hat perched atop Arthur's blonde head. As if to complete the ensemble, Arthur was smirking as he leaned against the doorframe, arms crossed.

"That's new," Merlin finally croaked, his eyes still stuck on the shirt. Arthur smirked, if possible, harder.

"A ground-breaking observation," he applauded dryly, pushing himself off of the doorframe. "What do you think? You were so against my old one, I figured it was time for a change."

"Change. Right," Merlin agreed distractedly. "'s good."

Arthur laughed, standing just a few feet away now, his own eyes raking up and down Merlin's frame, from the black boots and green tights to the black mask around Merlin's eyes.

"Really, Merlin?" he sniggered. "Robin?"

"What's wrong with Robin?" Merlin demanded, pulling out of his stupor enough to feel insulted.

"Of every superhero, you had to pick the one who's infamously gay," Arthur laughed. Merlin flushed.

"Robin's not the superhero," he pointed out sullenly, shuffling his feet. "He's Batman's sidekick." He tugged at his cape, suddenly self-conscious. Arthur, apparently sensing this, stepped forward, eyes still looking over Merlin's costumed body as he wrapped his arms around Merlin's waist.

"You know," he drawled, "I think Batman had the right idea, making Robin wear those tights. They are," he paused to lean forward, brushing his lips against Merlin's ear to finish, "very enticing."

Merlin squirmed, trying to hold on to his irritation but knowing it was a lost cause the second Arthur (the bastard) sucked his earlobe between his teeth. He gave up and allowed himself to lean into Arthur's touch, letting his own fingers play along Arthur's revealing neckline.

"We're going to be late," Merlin murmured, breath hitching when Arthur turned his attention to his neck.

"Yes," Arthur agreed, not bothered whatsoever. Merlin allowed him his way for a few more minutes, then, gathering his resolve, he detached himself, gently but firmly.

"Later," he promised at Arthur's displeased noise. "First, the party. There's no way I'm going to miss showing you off in that."

Gwaine's party was already in full swing when they got there. Arthur grumbled about having to park so far away, but Merlin just laughed and skipped ahead, forcing Arthur to jog to catch up. The house that Gwaine, Percy, and Elyan shared was covered in fake cobwebs, skeletons, and the odd headstone, with several people spilling outside onto the yard. Merlin and Arthur were greeted at the door by loud laughter and even louder music. Merlin beamed in delight. Arthur shook his head.

"The man can't resist showing off," he lamented.

"You say that every year, and every year you manage to enjoy yourself," Merlin scoffed. Arthur opened his mouth, but before he could reply, something pounced on Merlin, effectively tearing his attention away.

"You're here!" Gwen's voice trilled in Merlin's ear. He looked up to see her beaming at him through a rather impressive set of vampire teeth, a drop of fake blood staining the corner of her mouth. "Thank God. I was beginning to worry you'd left me to soldier through Gwaine's admirers alone."

Merlin laughed. "Hardly. Isn't Lance with you?"

"He went to get a drink," Gwen answered, and it was then that her gaze fell on Arthur. Her eyes widened comically. "Arthur? Is that…are you wearing a new costume?"

"Aye," Arthur quipped, grinning, and Merlin rolled his eyes. "I thought it was time for a change."

"I like it," Gwen said approvingly. "It's very…dashing."

"That's not the word I would use for it," Merlin mumbled, eyes giving Arthur another appreciative once-over. Arthur smirked, snaking an arm around Merlin's waist and tugged him close.

"You can tell me your opinion later," he whispered into Merlin's ear, sending a blush across Merlin's cheeks.

"Hush," he said as Lance approached, wearing a vampire costume to match Gwen's. Behind him strode Percy, catching the attention of several of the women with his muscular arms bare in his gladiator outfit, and Elyan, who had gone the traditional route and had outfitted himself as a zombie.

"Alright, Merlin, Arthur?" Elyan greeted them, and Percy raised his drink in salute. "Nice costumes."

"I thought you were going to be Merlin?" Lance added, gesturing at Merlin's Robin attire. "The other one, I mean."

Merlin made a face. "No. No wizard costumes for me," he said, purposely forgetting to mention the two (or three) years he'd dressed as Harry Potter.

His friends laughed. The night passed in much the same manner, their little group pressed together amongst the whirling crowd on the dance floor. They expanded easily when Arthur returned from grabbing himself and Merlin drinks with Leon in tow, laughing at his club bouncer outfit. Occasionally one or more of them would drift off, sometimes for another drink or sometimes for a round on the dance floor. Arthur even allowed himself to be cajoled onto the dance floor for a few songs, doing more laughing at Merlin's flailing dance moves than actual dancing. Merlin extracted his revenge by pulling Arthur close and swaying against him, staying just far enough away to be a tease, darting back away with a laugh whenever Arthur tried to bring them closer.

A few of their other friends made their appearances, as well. Elena, dressed as a jockey, waved at them on her way to the bar, and Freya dropped by for a few moments before she flew back onto the dance floor, the tail of her panther costume whipping behind her. In the haunted house (which was really just the upstairs hallway outfitted as a house of horrors), they found a zombified Gilli comforting a girl dressed as a witch, stealing sneaky looks down her corset. Merlin even caught a glimpse of Gwaine, predictably wearing a bare-chested Greek god costume, smiling silkily at a pretty girl wearing a sailor outfit.

Less pleasantly, a leather-clad Vivian cooed at Arthur for several minutes, completely ignoring Merlin, who spent the entire time wishing her ridiculous rabbit ears would catch on fire. He was immensely relieved when Arthur finally managed to shake her off, and even more pleased when Arthur spent the next several minutes making up for her presence with lips pressed against Merlin's jaw, hands curling possessively around his hips.

Merlin found himself standing progressively closer to Arthur as he downed more of his drink (which, he'd been delighted to discover, Gwaine had rigged to be pumpkin-flavoured). He was paying less and less attention to the conversations buzzing around him and more to the feel of Arthur pressed against his side, fingers running along the belt of his pirate pants and daydreaming of returning to their flat. Arthur must have been thinking along the same lines; Merlin could feel the heat of his fingers skating up and down his sides, and more than once Arthur leaned down to hum along to whatever song was playing beside Merlin's ear, placing soft kisses to the sensitive skin there.

Out of the corner of his eye, Merlin saw several girls throw sulky glances in their direction when Arthur laughed lowly into the shell of Merlin's ear, and he resisted the urge to flash them a smug smile, if only because it would inflate Arthur's ego.

Arthur bit down on Merlin's earlobe, and the girls were promptly forgotten.

"I've had enough of this party," Arthur murmured, his breath ghosting over Merlin's cheek. "Haven't you?"

Merlin grinned.

It took a remarkably short amount of time to drive back to their flat, and an even shorter time to wrestle each other out of their costumes. In no time, Merlin found himself flat on his back, Arthur's body flexing above his, gasping into his boyfriend's eager mouth. He hissed when Arthur's fingers pushed inside him, a little too soon in their excitement. Arthur rained apologetic kisses across Merlin's chest, paying extra attention to his sensitive nipples with his tongue.

Soon Merlin's raspy voice was begging for "more, Arthur, please, fuck", and then Arthur pushed inside and Merlin gasped and the pace was too fast, too impatient, but perfect, and Merlin was writhing beneath Arthur. His fingernails dug little half-moons into Arthur's back and Arthur's hips beat a rhythm against his. Merlin's toes curled and his back arched when Arthur hit his prostate, little gasps and soft "yes, Arthur, there"'s falling from his lips. He was dimly aware of Arthur murmuring his name into his shoulder, panting harder with every thrust of his hips.

When Merlin came, it was a surprise.

"Arthur," he huffed, gripping Arthur's arms too tightly, back arched in his release. Arthur didn't last much longer; a few more thrusts, and then he was shuddering, too, face buried in Merlin's shoulder, collapsing beside Merlin when he stilled, eyes still shut.

"Fuck," he wheezed, and Merlin groaned in agreement.

"I think you should hold on to that pirate costume," he remarked dizzily, turning to burrow his way into Arthur's arms.

Above him, Arthur laughed.