A special thanks to the lovely and talented gogo_didi over at livejournal for editing this sprawling romcom monstrosity. I swear, this was going to be 3,000 words of fluff, but then they would not just make out already, and lo, the UST took on a life of its own.

"Arthur," Merlin said loudly, competing with the sounds of bad seventies pop music blasting from Arthur's oversized speakers, "I don't know if you were aware, but your inability to put away your toothbrush isn't actually one of the endearing flaws that's convinced me to live with you."

"What?" Arthur shouted back, his voice distant and nearly drowned out by the sound of someone singing about piña coladas and inclement weather.

Merlin rubbed his temples. Between logging endless hours at the non-profit he claimed to work for and working an actual job, one that allowed him the luxury of things like toothbrushes, he was tired. And Arthur, despite his endless whinging about the trials of being the youngest VP in the history of Camelot Investments, was obviously getting enough sleep to be irritating well into the night.

"I said!" Merlin started, before turning on his heel and marching out of the bathroom and directly into—

Into Arthur. Suddenly, the music stopped, and Merlin wondered if he was the only one who heard his heart stop as well, then restart at an unnatural rate.

"You were saying?" Arthur said casually, catching Merlin's wrist where it was lodged in his armpit, stereo controller still clutched in his other hand.

Merlin swallowed thickly and awaited the inevitable return of his thoughts. They seemed to have migrated somewhere south of his brain right around the time the rest of his blood did likewise.

"About my toothbrush," Arthur encouraged with an annoyingly indulgent expression.

"Yes, and your shampoo and your aftershave and your—"

Arthur huffed.

"Something the matter, your highness?" Merlin chided, twisting his wrist out of Arthur's grasp and edging around his—alright, impressive—frame, into the living room.

"I should have known you'd be an absolute nag to live with," Arthur groaned, trailing after him.

"And I should have known you'd be too spoiled to pick up your own toiletries," Merlin replied, collapsing onto the sofa in a tired heap. "Honestly, did none of your nannies teach you to clean up after yourself?"

"I thought country boys were supposed to have manners," Arthur said, sprawling on the other end of the sofa with the enviable grace of someone with plenty of time to spend at the gym.

"Oh, here we go," Merlin moaned, flinging an arm across his face to block out the sight of Arthur looking smug and well-rested. It wasn't that he resented Arthur for being wealthy and almost illogically good looking, exactly. Most of the time the former didn't register and the latter was just sort of an incentive for putting up with all the things about Arthur that were truly and spectacularly annoying, like his bizarre obsession with weaponry and his apparent lack of domestic skills.

"No, seriously, Merlin, what would Hunith say?" Arthur asked. Merlin didn't need to look to know he was smiling.

"That you're an arse," Merlin muttered into his own arm.

Arthur snorted, and somehow it sounded haughty. "Your mother adores me. She's invited me round for Christmas, you know."

Merlin let his arm slide down his face enough to give Arthur a withering, if exhausted, glare. "This may come as a surprise to you, but not everyone is as in love with you as you are."

"Jealousy doesn't become you," Arthur sighed.

"She's my mother, Arthur. She still likes me better," Merlin groaned.

"Well, I suppose someone has to," Arthur conceded.

Merlin considered for a moment whether it was poor form to pass out on the sofa their first night sharing a flat, and he'd just about convinced himself that he was under no obligation to put out when he noticed Arthur flipping channels and giving Merlin an expectant look, though, fortunately, not his I'm Expecting Sex look.

"What?" Merlin asked tiredly.

Arthur shrugged without looking away from the screen.

It took a lot of effort on Merlin's part not to literally groan, partly because it felt overdramatic, but mostly because it was something Arthur would do. If being Arthur's friend and, at one point, his employee had taught Merlin anything, it was how to recognize a pout coming on, and this had the makings of an epic pout.

"Arthur, what are you doing?" Merlin said, scrubbing his face with the palm of his hand.

"I am watching telly," Arthur said, maintaining a disturbing level of interest in the rerun of Doctor Who he'd settled on, made even more odd by the fact that Merlin was absolutely certain they'd watched it together the night before in this exact flat, when it had been Arthur's and not theirs.

"Yes, I'd worked that much out for myself," Merlin said, making a concerted effort to maintain vertical integrity long enough to unknot Arthur's knickers. "But why are you doing it like you're trying to bore a hole through Freema Agyeman's head? Not that I object, mind you."

Arthur chuckled evilly. "Don't lie. She wore a lab coat one time, and you've been having filthy dreams about her ever since," Arthur replied, sliding his eyes towards Merlin.

"I have not! Some of us don't have career-based fetishes," Merlin said, giving Arthur a loaded glance.

"It's not a fetish. It's hardly my fault I look damn good in a suit," Arthur said, sounding far too confident for Merlin's liking and forcing Merlin to relive possibly the most unsettling moment of his entire adulthood, which had involved walking in on Arthur and a secretary and one of Arthur's painfully expensive ties being used in a manner Armani probably did not intend. It had been unsettling in several senses of the word.

Merlin chucked a pillow at his head.

"Hey! I thought you were so tired you could barely see straight," Arthur said, making a feeble attempt at pinning Merlin's arms to the sofa. It was obviously feeble because if he'd wanted to, Arthur could probably have taped Merlin to the ceiling without assistance.

"I'm rallying, as all great heroes must," Merlin said, wiggling out of Arthur's reach. Whatever dark cloud he'd seen pass over Arthur's face a moment ago was gone, and Merlin was grateful in ways he knew he shouldn't be.

That was sort of the problem, though, with moving in, with all of it. It wasn't that Merlin minded living with Arthur, or in Arthur's vicinity, or whatever they were calling it, it was just that he hadn't had much of a choice. It felt… dangerous, some how. Whatever they were doing, this surreal dance that made Merlin feel giddy and alive and, at times, completely delusional, had tapped into a part of Merlin he didn't usually acknowledge. The part of him that force-fed Arthur toast and tucked him into bed when he was well and truly pissed. The part that made sure Arthur remembered to go to the dentist and have his license renewed. The part of him that had a habit of subconsciously comparing his dates to Arthur, which in and of itself wasn't so terrible, except that his dates never seemed to measure up.

The part that was totally and utterly fucked.

Arthur eyed him suspiciously. "You're not staying up to humour me, are you?"

It took a moment for Merlin to work out what he was implying. "What? Wait, how am I…" And then Merlin noticed there was a bottle of champagne sitting forgotten on the table, and that Arthur was home on a Friday night instead of off doing whatever it was rich, pretty people did at the weekend. "Oh," he said quietly, "We're celebrating, aren't we?" Merlin fought the urge to smack himself in the head. It was just so typically Arthur that Merlin couldn't decide whether to laugh or be inappropriately pleased.

"Actually, so far, I'm drinking and you're harassing me about my toothbrush. But we could be celebrating," Arthur informed him.

"Me moving in? That warrants a bottle of champagne worth more that my life?" Merlin asked, a little bewildered, trying to repress the strange flush he so often got when Arthur did stupidly lovely things. Like buying him expensive champagne, or giving him a place to live without being asked, or, on one memorable occasion, threatening to skewer Merlin's date with an antique sword if he got handsy—which, alright, had been more stupid than lovely at the time, but in retrospect was just Arthur's slightly convoluted sense of chivalry, and therefore still rather sweet.

"Well, if it was worth less than your life, it would hardly be fit for human consumption," Arthur said, pausing to take a sip straight from the bottle. "Stop being such a girl."

"You're the one who bought champagne," Merlin said without much ire. "You do know I'm moving into your guest room, right? I'm not your live-in rentboy."

Arthur chuckled. "Not yet," he said, passing Merlin the bottle.

It took a good three seconds for Merlin's brain to stop screaming oh shit, what? and yes, yes, for god's sake, let's, simultaneously, and actually take the offered bottle, but he did, and with steady hands, he was pleased to note. After a long swig of champagne—taken from the bottle, because apparently real men had no need of glasses—Merlin settled in just in time to see some alien do something and then be defeated by the power of David Tennant's charm. Arthur threw his arm across the back of the sofa, and if it felt like his fingers tangled in Merlin's hair every now and again, it was probably Merlin's overactive, overworked imagination.

The first thing Arthur realised upon waking was that he wasn't in a bed. The second was that it was Saturday, which meant he could put off going into work to catch up on paperwork for as long as he bloody well pleased. His second thought was also his last thought for several blissful, unconscious hours.

The second time Arthur woke up, it was a lot less pleasant.

Something pointy had lodged itself in his ribcage, and there was definitely hair in his mouth, and it definitely wasn't his.

Arthur opened his eyes and waited for them to adjust to the ferocious sunlight streaming in through the blinds in his—in their living room. In his infinite wisdom, Arthur had purchased enough champagne to drown a small pony, or, alternately, leave Merlin passed out on his chest, fully clothed, snoring like a freight train, and drooling all over Arthur's favourite shirt.

God, this was so not a precedent he'd been planning to set. He wiggled a little and realised Merlin's weight had him trapped, pinned in such a way that there was no way of standing up without dumping Merlin onto the floor which, while appealing in theory, would only lead to a lot of yelling and possibly vomit on Merlin's part.

"Fuck," Arthur whispered, and then he went very still, because Merlin's eyes were suddenly open, and Arthur had to wonder when he'd started ninja training to allow him to wake up without so much as moving.

"And good morning to you, too," Merlin grunted out miserably. The effect was almost comical in conjunction with the way Merlin's hair curled and stuck up all over his head, and the fact that he had creases across his cheek where he'd been resting against Arthur's wrinkled shirt.

"You look wretched," Arthur couldn't help but point out.

"I look hung-over, you arse. And it's your fault. Now, what have I said about you being a prat before my morning coffee?" Merlin said, making no effort to disentangle himself from Arthur's limbs.

"If you don't want to wake up to my charm, you shouldn't pass out on my chest because you smelled alcohol," Arthur said, trying not the think about how well their bodies fitted together, or how rumpled and vulnerable Merlin looked just then. God, it wasn't like Arthur was some crazed sex-fiend or anything, regardless of what Merlin tended to imply, it was just that there was this thing that'd been going on for ages, quietly, blink and you'd miss it, but it was enough to drive Arthur out of his fucking skull. And now, Merlin was going to be living there, in Arthur's flat all the time, and suddenly Arthur realised he'd made a tremendous logistical error, because there were two things he knew for bloody certain: one, he didn't want to shag Merlin, because Merlin was his friend, and he wasn't going to fuck that up for anything; two, he really wanted to shag Merlin.

Something in Arthur's face must have given him away, because Merlin looked at him, frowned. "Oh god, you're not going to throw up on me, are you?" he asked, without moving.

Arthur smiled. "If I did, it would only be in vengeance for New Years."

For a moment, Merlin looked unconvinced. He peered down at Arthur, as if checking for signs of impending illness. Then, their eyes met, and Arthur stopped breathing because their faces were a lot closer than they had been a second ago and something had to happen soon or he was going to explode. Finally, Merlin let out a resigned huff and closed the gap between them.

Arthur's entire body seized up like he'd been electrocuted. Merlin's mouth was on him, biting at his lip and sucking and, Christ, that was his tongue and it was doing some pretty interesting things, things Arthur would never have thought clumsy, hopeless Merlin capable of, but still, his brain was going off like an air-raid siren. It wasn't that he had any objection to doing stupid things with inappropriate people, as half the interns and two of the VPs at Camelot Investments would happily attest, he just preferred to do them while everyone involved was drunk enough that no one could be held responsible. And while he had to admit that this was better than a drunken tumble— all right, a lot better, and just what in the fucking fuck was Merlin doing with his mouth?— the downside was that Arthur was sober and so was Merlin, and it was morning, which was going to make waking up and pretending it never happened a lot trickier.

Merlin pulled away and frowned. "Alright, I'm going to interpret your lack of enthusiasm as surprise and not soul-crushing rejection, yeah?" he said calmly.

"Merlin…" Arthur attempted.

"Ok. Perhaps I'm being optimistic here," Merlin said, pulling away and offering a half-hearted smile that utterly failed to reach his eyes.

Arthur sighed and was sort of shocked to realise his fingers were tangled in the hem of Merlin's shirt. He let go, but there wasn't enough space for two fully grown men to lay side by side on the sofa, no matter how large and comfortable it was, or how skinny Merlin was. This was despite Arthur's best attempts at making sure he ate (usually in the form of lunch dates and take away curry consumed on the sofa in question). Their legs were tangled, and Merlin was still half on top of him, and the way Arthur's arm was pinned beneath Merlin's side was uncomfortable for everyone involved, but Arthur still sort of thought he wouldn't mind staying exactly as they were, which was, come to mention it, exactly the problem.

"Perhaps you are," he said quietly. Because really, how often did these things work out? Romance novels and soppy movies aside: just about never in Arthur's experience.

Merlin jerked back abruptly, cold air rushing into the body-warm space he'd been occupying on Arthur's chest. From the look on his face it was clear Merlin didn't care for his answer. "Look, I'm going—going over to Gwen's. See you later, yeah?" he said, standing up and grabbing his ridiculous messenger bag from the counter by the door where they had a tendency to shuck their things upon entering.

"Wait," Arthur called after him, an inexplicable twinge of panic shooting through his gut without explanation.

Merlin turned to him, eyes wide and uncertain, one hand already on the door.

"Arthur?" he said quietly.

Suddenly, the room was very still and Arthur felt like he'd fallen into an alternate universe, where the stupid shit he said might actually matter. This made it a tremendous shame that he had absolutely no idea what to say. "It's—" he tried, feeling completely inadequate without warning. He swallowed hard. "Don't forget your new key," he said softly.

Merlin blinked at him, and for a split-second, he looked almost disappointed, but in a flash it was gone. "Right," he muttered, grabbing the key from the countertop, "Thanks."

Before Arthur had a chance to regroup, the door slammed shut, and Arthur fell back against the sofa with miserable grunt.

Oddly enough, it took almost no time at all for things to go back to normal. Actually, if Arthur's behaviour was any indication, there had never been anything abnormal about them in the first place, and there was no way in hell Merlin was going to be the one to scream there is there is you unbelievable idiot, no matter how badly he wanted to. He should have been accustomed to it by then, the mounting tension, the loaded glances, the complete and utter failure to launch.

In fact, Merlin had intended to point all of this out just as soon as he was finished telling Gwen so she could pet him and call him a moron and a man in her most soothing tones, but by the time he went home—and god, wasn't that inconvenient—Arthur was making dinner with Merlin's favourite Coltrane album playing in the background, eager to chat about football and stocks, and not the weird, annoying outbursts of homosexuality they appeared to trigger in one another. Hell, perhaps Merlin had finally cracked under the pressure of working two jobs and dealing with Arthur Pendragon, pratliest prat in all the land, and the whole thing had been a figment of his tired, over-sexed imagination.

Except, it hadn't been. Because for all that they clearly Were Not Discussing It, Arthur hated jazz, and he was making (and ruining) Merlin's favourite pasta.

Within a week, Merlin could almost pretend he didn't remember the way Arthur's fingers felt tangled in his shirt, or the hard warmth of his chest beneath Merlin's own. After a month, he even regained the ability to brush past Arthur without getting an unbearable, near-instant hard-on.

They settled into a comfortable routine. Most mornings, they had breakfast. Merlin cooked eggs or bacon, sometimes both, while Arthur handled toast and juice – or, as Merlin put it, things that weren't poisonous in the hands of helpless yuppies who didn't know a wok from a wank. In the evenings, when Merlin wasn't on call and Arthur didn't work late, Merlin puttered around the kitchen, usually griping about their appalling lack of groceries, and emerge with some form of sustenance, which they ate in the living room while Merlin watched telly and Arthur read one of his frightening books about finance. Except for evenings Merlin came home tired (well, more so than usual) and cranky, then Arthur would disappear for a while and return bearing cartons of Chinese and, more often than not, a six-pack, and they'd spend the evening arguing over the last egg-roll, which inevitably devolved into chop-stick sword fights that Arthur always won.

It was a nice life, Merlin supposed, if only that.

Living with Merlin was a bit like having a maid with an attitude problem. For every home cooked meal Arthur got out of the arrangement, there was a scathing comment about Arthur's dietary habits. For every freshly laundered shirt that appeared in Arthur's closet as if by magic, he'd find one of his ratty old hoodies missing, only to discover it hanging off Merlin's bony frame where he lay curled up and snoring on the sofa. They never discussed the rent, because it was distasteful, and every time Merlin brought it up, Arthur was forced to suffocate him with a pillow.

Everything was going well, considering, and Arthur knew he should just shut up and leave well enough alone, but sometimes… well, sometimes he had thoughts.

Like what life would be like if lazy nights in with Merlin were actually lazy nights in bed with Merlin. Like how it would feel to pin Merlin to the floor without the excuse of a lone egg-roll Arthur didn't even want.

It was worse in the dark. Arthur would lie in bed and ponder the weight of Merlin's legs draped over his shoulders, calculate how much of Merlin's skinny waist he could span with his hands, muse over whether Merlin would be loud and obscene or quiet and trembling beneath him, his skin white and infinite under Arthur's mouth, sweating and panting Arthur's name into the crook of his neck while they—

And then there were the glances.

Sometimes, when he wasn't trying, Arthur would catch Merlin just looking at him, like he was thinking the same stupid, impossible thoughts, like maybe Arthur was wrong to have dismissed the idea, because what's a little fantastic, life-altering sex between friends?

Sometimes, Arthur could almost convince himself it was that simple.