Arthur lost a bet.

That's why he ended up wearing what he was wearing and absolutely not because he wanted to.

Really.

It also didn't have anything to do with his boyfriend's not-so-subtle hints when they were out shopping that Arthur would look good in those panties or that mini-skirt or this black lace top. Arthur always shot down those suggestions with a good-humored laugh and hasty change of topic, not at all eyeballing the lace with a stirring of curiosity and want.

No, his current outfit was just the product of an ill-made bet while playing Sunday Night Poker with his sister, Morgana, and her wife, Gwen. Morgana was bluffing her way to victory, or so Arthur thought, and just before they showed their hands, she said, "Do you remember when you were like, thirteen, and Uther walked in on you trying on my lacey panties?"

Arthur stared at her warily over his cards while Gwen broke out laughing.

"Perhaps," he said. "Why?"

"If I win, I dare you to wear full-stop girly lingerie, of my choosing, for a full day."

"And if you lose?"

"Then I'll tell your pervy friend Gwaine where to find my amatuer porn online."

"Deal."

He lost.

Gwaine punched him in the left nut.

Morgana gave him lingerie.

She stopped by his house early on Tuesday and handed him a small bag that couldn't possibly hold everything he'd need. Then she simply patted his arm, reminded him to take a picture every hour for proof, and left.

And thus, six hours later when his boyfriend came home from work, Arthur was not in his usual white cotton shirt and boxers. He was wearing hot pink, candy-striped stockings with a little bow on the top of each thigh, and they were connected by pink garters to white, frilled boyshort panties that were also topped with a small bow above his crotch. The final touch was a hot pink lace corset that took him damn near an hour to lace up properly.

In every 'proof picture' he sent to Morgana, he was flipping her off and glaring.

Confronting his boyfriend, however, was another story.

Merlin came home just after six, like he always did, and took off his shoes and coat in the doorway. Arthur visualized Merlin's progress from where he lay upstairs on their bed. Tie off in the living room. Notice Arthur wasn't there. Wander into the kitchen. Arthur wasn't there either. Then there was the soft patter of footsteps on the stairs. The bedroom door creaked open. And Merlin stopped.

"Oh my god." Merlin brought his hands up to his mouth, and Arthur nearly laughed when he saw tears forming in his dark blue eyes. "Is it my birthday?"

"No," Arthur said roughly, hoping his sudden rush of embarassment didn't show on his cheeks. "I lost a bet to Morgana."

"Holy christ." Merlin inched closer to the bed, like he was afraid Arthur might disappear or run away any moment. "She's getting the best Christmas present this year, I swear."

Arthur rolled his eyes. "Shut up and come here."

Merlin obeyed, crawling up on the bed still clad in his dark grey button-up and black trousers and socks. Arthur didn't tell him to take it off. If he had to stay partly dressed, then Merlin did, too. The bed creaked a little as Merlin crawled between Arthur's splayed open legs, rubbing his hands gently over the pink stockings and biting his lip. He looked like a child who just got his favorite toy and didn't know what to do with it first.

Arthur frowned and bent one knee to nudge Merlin's side."Are you just going to stare at me all night?"

"I might," Merlin said seriously. He ran his hands up Arthur's thighs and over the panties, stopping to caress the frill-covered hips. The way he was staring, heavy-lidded and wanting, made Arthur's cock twitch.

Merlin licked his lips and bent down to kiss the bit of bare skin between the stockings and panties. He kissed his way up over the bulge of Arthur's hardening cock, stopping to nip him a bit over the soft fabric, then moved up to press a kiss just under the corset while his fingers hooked over the band of the panties and pulled them down to Arthur's thighs.

Arthur inhaled sharply as Merlin licked the underside of his cock with a lazy familiarity and lapped playfully at the tip. He teased there for a while, like he always did, kissing and sucking lightly and blowing small puffs of cold air until Arthur groaned impatiently and bucked up. Merlin sank down, then, taking Arthur's cock all the way to the back of his throat before swallowing and sucking and bobbing his head.

He sucked Arthur off purposefully, almost violently, using one hand to hold Arthur's hip and the other to gently roll and massage his balls while his lips went to work. Arthur almost couldn't breathe from all of it. The warm heat of Merlin's mouth on his dick and the bruising hand on his hip and the gentle fingers on his nuts assaulted him with pleasure, building the tight anticipation of his release much sooner and more desperately than he would've liked. He clutched the bedsheets in his hands and tensed, curling up, crying out, and then -

"Fuck!"

Merlin pulled off just a moment too soon and quickly snapped the panties back into place. Arthur threw himself back onto the pillows and groaned.

"I'm gonna fucking kill you!" Arthur snapped. He buried his head in a pillow and resisted the urge to scream.

Merlin smirked and wiped his lips, his eyes trained hotly on the bulge under Arthur's soft panties.

"Shut up," Merlin answered, voice rough and low. "Turn over."

Arthur quickly did as he was told, resituating the pillows so one was under his stomach and one between his head and the headboard. His erection ached, and he deftly humped the pillow a bit to soothe himself. Merlin, meanwhile, could be heard grabbing the lube from their nightstand and unzipping his trousers.

"Fuck, your ass looks so good like this," Merlin said lowly. Arthur could hear the wet fap of him pulling on his dick with lube. One of Merlin's hands reached out and massaged Arthur's left ass cheek at the same time a kiss was placed on his right. Arthur humped into the pillow again.

"My ass would look better with your cock in it," he said irritably, glancing back to give Merlin a well-earned glare. Merlin smirked and bit ass playfully.

It was only a moment later that the panties were pulled down again, and Merlin's slicked up fingers started working open Arthur's tight hole.

Arthur hated prep. He only saw it as wasted time that he could have an actual dick inside him, but Merlin was all about safety and you'll hurt yourself Arthur and refused to fuck him otherwise, so Arthur waited through it. Not without impatience, though. Merlin pressed in a third finger and Arthur fucked back, stretching himself hastily.

"Please just fuck me," he groaned into the pillow.

He could practically feel Merlin's eye-roll, but he knew that Merlin also couldn't resist him saying 'please.' The fingers disappeared. A moment later, the tip of Merlin's cock pressed in.

Arthur gave up all pretense of being 'cool' and 'macho' in bed a long time ago, so he didn't feel any embarassment over whimpering and begging Merlin to hurry the fuck up and get in him.

"Please. Yeah. Fuck me, Merlin, come on."

Merlin snapped the rest of the way in, done over by Arthur's little moans, and Arthur felt the touch of Merlin's belt buckle on his thigh. Merlin hadn't even bothered taking off his trousers, he wanted Arthur so badly. Something about that turned Arthur on even more.

Merlin held himself balls-deep for a moment before starting to slowly work himself in and out. Beneath him, Arthur writhed, clutching the sheets and fucking back and wanting to hump the pillow at the same time. Merlin always started out slow and savoring, and Arthur had to work to get him out of control. He clenched around Merlin and brought his knees up to make himself tighter.

"Shit," Merlin breathed, hips stuttering.

He fell forward, hunkering down over Arthur and leaning flat-palmed on the bed. His hips jerked faster but not nearly hard enough. Arthur clenched again and grabbed one of Merlin's hands, pulling him further down.

Merlin grunted softly and finally relented to give Arthur what he wanted. He draped himself over Arthur's back, leaning on one elbow locked in front of Arthur's shoulder while his other hand pressed flat against the headboard. He used the leverage to rock into Arthur hard, shaking the bed and slamming the headboard into the wall.

Arthur keened.

He could feel Merlin deep and pressing hard inside him, and coupled with the pressure of his dick against the pillow and the rough rub of lace against his nipples, Arthur was driven up the wall. He clutched wildly at the sheets and bit down on the pillow in front of him to muffle the onslaught of tiny, whining moans pouring out of his mouth. He could feel Merlin like a furnace at his back, hot and sweating underneath his oxford shirt, all the way down to the arm pushing back on Arthur's shoulder, shoving him back hard onto Merlin's cock.

The pace got more crazed as the tension built, until Merlin let go of the head board and pinned Arthur down with both arms, fucking into him hard and brutal. Three. Four. Five more thrusts and Arthur curled, cried out, and came, his hole clenching hard around Merlin's dick even as he kept fucking a few seconds more, the headboard knocking a few more times before Merlin came with hard-pressing hips and a soft whine in Arthur's ear.

They trembled and took deep, panting breaths in the aftermath. Arthur was very nearly dead to the world when Merlin slid out of him and leaned back, supposedly for clean-up. But when Arthur didn't feel any assistance coming his way, he forced himself to look back curiously. Merlin was sitting at the end of the bed, cock still out and half-dressed, taking pictures of Arthur with his phone.

"Next time you go on a business trip," he said, "I'll be wanking to these furiously and often. Just so you know."

"Okay," Arthur answered, uncaring and tired. He closed his eyes to pass out, but Merlin nudged him.

"Turn over."

Arthur sighed and obliged, peering at Merlin with hooded eyes as he splayed out his legs for better viewing. The panties were still shoved down on his thighs, leaving his dick out and glistening with cum. He tried not to smirk as Merlin's cock twitched again at the sight.

"You know," Arthur said conversationally, "you should send one of those to Morgana. She'll ask for a proof picture soon, to make sure I'm still wearing it."

Merlin's eyebrows rose, and he glanced between Arthur and his phone doubtfully. "Seriously?"

"The dirtier the better. She'll never bet me anything again."

"There's something very wrong with you."

"Says the man taking dirty lingerie pictures on his mobile."

"Shut up."

Arthur laughed. "I love you, Merlin."

"Love you, too, asshole."

"Good. I'm changing into pajamas, then."

"Damn."