A/N: I got sidetracked from my current WIP by a comment fest over on Live Journal. I was missing writing about these boys so it was nice to have an excuse to get back to them for a bit.
The prompt is at the bottom (snigger) as it contains spoilers.

Warnings/promises: Almost entirely PWP, explicit adult content.

"Merlin, bring the towel, I'm finished with my bath," Arthur's typically imperious voice rings out as he stands up in the tub.

Water streams from the Prince's naked body. He stretches out his arm impatiently as Merlin hurries for the towel that has been warming by the fire.

Merlin keeps his eyes carefully above Arthur's waist as he spreads the towel out for Arthur to wrap himself in. The air is chill despite the roaring fire in the grate and Arthur's nipples are small and tight with the cold. Merlin swallows and forces his gaze higher.

Arthur dries himself and moves to where his sleep clothes are laid out, dressing himself quickly in the soft leggings and loose shirt. He towels his hair roughly and arranges it with his fingertips then stops and examines his nails. He frowns in dissatisfaction.

"Bring my nail cutters and file, Merlin."

Merlin is familiar with this part of the ritual. It is one of Arthur's oddities that he finds strangely endearing – not that he would ever let his master know this of course.

Arthur is nothing short of obsessed with his fingernails. He always has Merlin cut them as short as he can whenever they are soft after bathing. Once they are cut, Merlin has to file away any jagged edges until they are smoothly curved to the Prince's satisfaction.

Merlin moves to his master's side and takes Arthur's proffered hand. It is warm and dry with golden skin and broad, thick fingers. Merlin's own hand looks pale and ludicrously slender in comparison. Arthur's palm is calloused from wielding a sword and the back of his hand is dusted with fair hairs that catch the warm light from the fire and candles. Merlin is so familiar with Arthur's hands after months of performing this duty for him, that he thinks he could recognise them by touch alone.

He holds Arthur's hand carefully and rests it on the edge of the table where they sit. He curls his fingers around the Prince's and separates them carefully. The spring scissors that he uses to clip Arthur's nails are lethally sharp. Merlin isn't known for his dexterity so he always feels nervous when carrying out this particular duty. But it's not just the risk of harming Arthur that makes him nervous and uncomfortable. The proximity and intimacy of the situation make him want to squirm in his seat every time.

Merlin can almost feel Arthur's breath on his cheek and he feels a familiar heat flood to his groin. Not for the first time he bemoans the fact that he finds his own sex attractive and curses the gods for dishing him out the cruel destiny of having to serve such a perfect specimen of manhood. If Arthur wasn't so beautiful, Merlin's life would be so much easier.

Merlin gets through the next five minutes by thinking determinedly of what Gaius might look like naked. He breathes a heavy sigh of relief when he's finally completed the task to Arthur's exacting standards.

"There," he finishes, filing away the last sharp edge of newly cut nail on one of the Prince's little fingers and sits back, releasing Arthur's hand from his grip.

Arthur spreads out his fingers and admires Merlin's work. He tests his nails for smoothness by running the edges lightly along his lower lip, making Merlin flush with heat as he watches curiously.

"Thank you, Merlin. I'm going to retire now." Arthur stands and moves towards his bed. "I need to be up at first light tomorrow for training, see that you wake me."

"Of course, Sire."

Merlin moves to snuff the candles, extinguishing all but the one mounted on the wall over the Prince's bed, casting a pool of light that glows on the Pendragon-red bedspread and drapes that surround the bed. Merlin leaves the room and closes the heavy door behind him.

XOXOXOX

It isn't until Merlin is dressed in his own sleep clothes and crawling between the cold sheets of his narrow cot, that he realises he has forgotten to bank the fire in the Prince's chambers. He sighs in frustration but knows he will have to go back, or the fire will go out in the night and it will be bitterly cold in the chambers at dawn when he goes back to wake his master. Arthur is never in a good mood when he has an early start and Merlin doesn't want him to have any reason to be grumpier than usual.

Cursing his forgetfulness, Merlin pulls a cloak around his shoulders and pads back out into the darkness, not bothering with his boots. The flagstones are bitingly cold under his bare feet so he hurries through the dark corridors, the flame of his candle casting shifting shadows on the stone walls.

Merlin is expecting Arthur to be asleep and hopes that he can creep in without disturbing him. He pushes the door open and slips in like a shadow, his feet silent on the bitter floor. He closes the door gently behind him.

The room is dimly lit with a red glow and Merlin realises that the candle over the Prince's bed is still burning. He tiptoes over to snuff it. The dark red curtains that surround the bed hang closed against the chill of the night, save for a hand-width gap at the foot. As Merlin reaches the bed he hears a quiet huff of breath and a whisper of movement. He freezes, fearful that he has woken the Prince. He peeps through the gap in the curtains and his legs nearly fold under him as all the blood in his body pools somewhere in the pit of his belly.

Arthur is most certainly not asleep.

He is lying, naked and gleaming with sweat on top of his bedspread. His legs are spread wide, knees pulled up and his body glows golden in the soft light of the candle that has transformed the curtained bed into a warm red cave. One of Arthur's hands is wrapped around his cock, gripping and tugging slowly in an almost imperceptible movement. The other is reaching down between his thighs. Merlin watches, mouth dry, floored by a shocking jolt of want, as Arthur works two of his strong fingers in and out of his hole in an urgent, impatient rhythm.

Merlin is rendered completely unable to move or breathe. It crosses his mind that if all the blood in his body has rushed to his prick, it is entirely possible that there won't be enough left for the rest of his body to function. He wonders what will happen if he collapses on the floor of Arthur's chambers, killed by lust. Maybe this would be a good thing, because he is apparently paralysed and can't stop watching and it's all so horribly, wonderfully wrong.

Arthur moans and curves his body awkwardly. His face is crumpled with frustration, eyes clamped shut. He cranes his arm around further and hisses, trying to push deeper into his arse. Merlin can hear the slick slide of his fingers and is transfixed by the delicate stretch of skin around Arthur's knuckles as he moans and strains. Merlin's prick twitches in sympathy.

Before he knows what he's doing, Merlin finds himself moving, pushing the curtains aside and crawling onto the bed between the Prince's legs. Arthur's eyes snap open as the bed dips, but Merlin is on him before he can speak. He soothes Arthur with gentle touches to the backs of his thighs and murmurs softly.

"Shh... it's okay, Arthur. Let me help you."

"Merlin... I..." Arthur gasps. His eyes are wide, cheeks splashed with the colour of shame and helpless arousal.

"Shh," Merlin hushes reassuringly, sliding his hands down to spread Arthur's thighs impossibly wider. "I can see how much you need this. Let me."

He curls his fingers around Arthur's wrist and pulls gently. Arthur makes a keening sound as his fingers slide from his body, his hole twitches at the loss. He stares at Merlin, chest heaving as Merlin parts his lips and slides two fingers into his mouth, hollowing his cheeks and sucking until they are shiny wet.

Merlin lowers his hand and slowly inches his fingers inside. The Prince's arse is already loosened and they slip in easily to the knuckle. Merlin moves them in and out carefully, entranced by the sight of his pale fingers being swallowed so greedily. He presses in further, deeper than Arthur had been managing with his own hand and is rewarded by a needy whimpering sound, so unlike anything he has ever heard from his master's lips that it makes him grin with wild delight.

He starts to pump his fingers now, pushing harder and curling them upwards until Arthur stiffens and cries out, his mouth a beautiful 'oh' of surprise. He shudders and his hole flutters around Merlin's fingers. As Arthur's hips buck, the head of his prick pushes through the tight clench of his fist and spills, white and sticky on his belly.

Merlin keeps on moving his fingers as Arthur rides out his orgasm, until his body is limp and his breathing begins to slow. Then, and only then, Merlin allows his fingers to slip out, the cold air is a shocking contrast to the heat of Arthur's body. Merlin lifts his eyes at last and Arthur is gazing at him intently. There is a softness to his features that Merlin has never seen before.

Arthur reaches out pulls Merlin down beside him, tugging at his clothing until Merlin's cock is exposed. They lie facing each other and Merlin tucks his face into Arthur's neck and twines his fingers into his hair. He inhales sharply as strong fingers wrap around his cock and start to move. Arthur smells of soap and sweat and musk and Merlin puts out his tongue to taste it, licking at the Prince's neck like an animal. Arthur's thumb flicks over the wet head of Merlin's prick and he comes, biting down on Arthur's skin as he shudders and the world around him swims out of focus.

They lie, tangled and sticky, sweat and semen cooling on their bodies until the cold drives them to rearrange themselves under the covers. Merlin's head is blissfully empty of thought. He takes one of Arthur's hands and meets no resistance as he holds it and idly plays with the Prince's fingers, running his own fingertips over the perfectly manicured nails.

"I always wondered why," Merlin suddenly murmurs with a grin.

Arthur just chuckles and pulls Merlin's hand up towards the candlelight, examining his short, but slightly ragged nails. He tuts disapprovingly and shakes his head.

"You can add keeping your nails filed to your list of duties from now on, Merlin."

"Yes, Sire." Merlin hides his delighted smile against Arthur's neck.

FIN

A/N: Prompt: Arthur makes Merlin trim his (Arthur's) nails and Merlin doesn't know why he's so obsessive about it, until he walks in one day to see Arthur fingering himself.

Let me know what you think, and if you liked it – check out my other stories. Some of them even have plot.