Disclaimer: Characters and settings remain the property of their respective creators. I'm just playing.

A/N: For Eumelkeks. You inspired this one, bb.

"Edward Cullen, I'm here about the outbreak."

Merlin blinked at the stranger who had just appeared in front of him. He was used to odd things happening around him, but even so someone materialising in his bedroom before he was properly awake was a little startling, whether or not it came with a formal introduction. He rubbed at his eyes, trying to banish the last vestiges of sleep and make the words the stranger had uttered mean something.

Edward Cullen stared at him, still waiting for a reply, and Merlin swung his legs off the bed, trying to arrange his thoughts into words. "Th-the what?"
"With the unicorns. And the vampirism."
"Th – the – "
"I'm sorry, have I dazzled you? I do that – I don't mean to – "
"What? No, it's just – I didn't know there was a problem with the unicorns."
"Oh, am I early?"
"I don't know. Gaius!"

His voice was not the nonchalant tone he'd been hoping for, more a theme and variation on panic, but still Merlin looked towards the door, hoping that Gaius would come and rescue him. Gaius appeared in the doorway.

"Merlin, what on earth – "
"There's a man here about the unicorns. And the vampirism?"
"Ah, Edward, good to see you."

Merlin gaped as Gaius and Edward embraced, Gaius' hands lingering a little too long on Edward's shoulder, Edward shuffling in an embarrassed fashion as he noticed Merlin's open mouth. "I see you haven't quite explained things," he said, and Gaius rolled his eyes.
"I was going to over breakfast but apparently someone thinks they deserve a lie-in. Edward, this is Merlin. Merlin, late last night I was out in the forest looking for supplies and I saw a terrible sight – a trail of blood leading to where I know unicorns have been living."
"Something's killing unicorns?"
"I'm afraid it's more serious than that, Merlin. The unicorns have turned."
"Turned? Into what?"
"Vampire unicorns."

Edward and Gaius shivered in horror, and Merlin eyed them both cautiously. "What's that mean?"
"They're very dangerous. They use their reputation as harmless creatures, ambassadors of hope and light, to draw people to them and then – "

Gaius mimed claws, baring his teeth and sinking them into thin air.

"They drink blood, Merlin," Edward said.
"Oh, well no problem. I'll just get Arthur and the knights to kill them, then."
"It's not as easy as that."
"Why not?"
"Well," Edward said, meeting Gaius' eye, "only people who are – "
"Pure of soul."
" – can kill them."
"Arthur's pure of soul."

Gaius sighed, his fingers flexing and his jaw tensing in what appeared to Merlin to be embarrassment.

"He's not, Merlin. Not in the way I mean. I'm afraid people capable of killing a vampire unicorn are few and far between."
"Which way do you mean? If Arthur's not pure of soul I don't know who – "
"What Gaius means," Edward said, "is that to kill a vampire unicorn, a person needs never to have known the pleasures of the flesh."

Merlin swallowed. It was a bizarre discussion to be having before he'd even had his breakfast.

"You're saying Arthur's not a – "
"Not for a long time, Merlin. But Edward here has all the skills required."
"You mean you're a – "
"In spite of Gaius' best efforts, yes."

Edward and Gaius exchanged a slow, knowing look, Gaius' eyes twinkling with unmistakable flirtation, and this time Merlin did shiver with horror. The best – the only – course of action seemed to be to get this whole matter dealt with as quickly as possible so he could go back to thinking the only thing Gaius had ever done with his lips was purse them in annoyance. "How do we kill them, then?"
"Thank you, Merlin, for saving me the embarrassment of asking the question."
"You said we, implying that you too – "

Merlin flushed and avoided Gaius' eyes. "It's not like I haven't had chances – it's just I'm always busy and – it's not easy when you have to stand next to Arthur all the time. Sometimes I think his armour's so shiny people can't even see me through the glare."

He chanced a glance at Gaius to find him smiling softly. "Your secret's safe with us, Merlin."

An hour later Merlin was trudging through the forest, trailing after Edward Cullen and trying to avoid snapping an ankle in a rabbit hole. His face had dwindled from puce to a pale pink, but the thought of Gaius knowing, knowing that, rang in his head like a bell.

And of course Arthur had done it. Of course he had.

Merlin dug his fingernails into his palm, forced his lips together as if that would diminish the unfairness of the world, momentarily lost his footing and angrily stumbled into a tree. "Oh for f – "
"There's nothing wrong with it," Edward said, offering him a hand.
"Being a virgin."

Merlin let Edward pull him back to his feet, marvelling at how strong he was, how easy all this seemed to him. And in the dappled light of the forest he was –

Edward smiled slightly, and as their fingers lingered Merlin felt a fresh rush of embarrassment that was nothing to do with Gaius. "So when we find these vampire unicorns, how do we kill them?" he said.

Edward let go of his hand, gestured that they should get going again, and Merlin wished he hadn't spoken.

"We sing to them."
"Sing to them?"
"You have a problem with that?"
"No – I was just expecting a beheading or – fire – something, you know, traditional. And – gory."
"Oh there'll be gore," Edward said, pinching the bridge of his nose.
"When we hit the right note they explode."

The trees thinned, and, right where Gaius had described it, there was a crimson trail leading to the caves the unicorns had been dwelling in. Merlin peered into the gloom, watching for any sign of movement, and at his side he could feel Edward tense. "We need to entice them out," he said.
"How do we do that?"
"Easy. Blood."
"Blood. Ok. Did you bring some?"
"I meant yours."

There was little Merlin wanted to do less than spend his Sunday morning slicing open his hand to entice a bunch of deadly vampire unicorns out into the open, and yet he found himself staring at his own palm and whispering the incantation to tear his skin. Edward winced and then met his eye with a smile, and Merlin swallowed, watching as blood blossomed out of the cut.

"Unless they're ravenous it'll just take a moment for them to – "

In the cave, something glinted, something that looked an awful lot like –

Teeth. Several sets of t – no fangs. Giant, pointed, terrifying fangs.

Merlin screamed. The unicorns charged, their eyes blazing a vindictive red, and as they hurtled towards him they bared their fangs in a brutal, primordial sneer.

Merlin knew he was done for this time. At his side, Edward Cullen took a deep breath, and he knew they were thinking the same thing: here, now, they were both going to die a couple of pathetic, tragic virgins, in the most horrific way possible.

There didn't seem any point in running, and so Merlin braced, closed his eyes, allowed himself a flicker of a daydream as his last mortal thought, his lips against –

There was a noise, a high, careening kind of wail that wasn't the sound of anguish, of someone being bitten by a crazed vampire unicorn, but something piercingly lovely. Merlin opened his eyes, looked at Edward to find him poised on his toes, the sound emanating from his mouth and a look of quiet serenity on his face. The unicorns stalled, their lips quivering over their long, triangular teeth, and twitched. Edward gestured frantically for Merlin to join in, and so obligingly he took a breath.

His first note was more of a strangled 'nnugnarrrrrrrrrrrgh' than anything of any particular beauty, but he tried again, eventually working his way up the scale until he and Edward were in perfect harmony.

The closest unicorn shook, its eyes burning with rage, and then, without warning, it burst. Merlin blanched as blood and what felt distinctly like part of a lung splattered across his face, and he watched as four hooves and a horn dropped with a series of unceremonious plops onto the grass in front of them. The unicorn's thin blood rained down from the trees, but they kept on singing, linking hands to fortify themselves.

One by one the unicorns met the same fate, exploding and raining down on the forest, the only memory of them their horns as they shuddered to a halt on the grass. Exhausted and hoarse, Merlin collapsed on the ground, and after a moment's rest a laugh burbled in his stomach.

They'd done it. They'd actually done it. He and Edward.

He looked up, and there, illuminated by a shaft of sunlight and dripping with unicorn innards, stood Edward Cullen. Merlin didn't know if it was the explosion doing things to his eyes, but Edward's skin seemed to be shimmering, and something unfamiliar but welcome twisted in his stomach at the sight of him.

But Edward wasn't smiling, and there was no flicker of relief in his eyes that the unicorns were now nothing but mush. Merlin got to his feet, edged closer, and Edward flinched, looking away.

"Don't look at me, Merlin. I'm hideous."
"It's just innards. Bit of spleen in your hair, it'll wash off."
"I meant my – my skin."

Edward met his eye, his gaze full of shame Merlin couldn't understand. What they'd just done was brilliant, and they'd saved people. Edward had saved him. "What?"
"This is the skin of a killer, Merlin," Edward said.
"Yeah I know. A vampire unicorn killer."

Merlin launched himself at Edward, and at first it was more of a collision than a kiss, because beneath his blood-sodden clothes Edward was apparently made of granite. But Merlin didn't care. His lips sought and found Edward's, and after a startled second he responded eagerly, pushing his fingers into Merlin's hair and dislodging whatever unicorn bits had settled there. It was dizzying, and they tumbled to the ground, making a faint splatting sound on the damp grass.

In an instant things were more urgent, a tangle of breathless, enthusiastic kisses and curious hands that made it all too easy to forget they were lying in the aftermath of a massacre. Merlin moaned, wanting more, and he pressed his palm to the taut plane of Edward's stomach, moving lower. Edward shifted into his touch, but when Merlin's fingers loitered on his belt, Edward's cold hand closed around them, stilling their progress. "What?" he murmured.
"We can't, Merlin."

Edward looked up at him, his expression one of aching regret beneath the blood spatter.

"Because of Gaius?"
"No, because of the unicorns. You heard what Gaius said. We need to – hold onto our virtue in case – "
"You mean I have to stay a virgin forever just in case Camelot gets attacked by vampire unicorns?"
"Basically, yes."

Edward smiled up at him ruefully, then affectionately picked a bit of pale grey unicorn skin out of his hair and flicked it away. "It's not so bad once you get used to the idea."

Merlin glared at him. "This is so unfair," he said. "Time after time I save Camelot – and no-one knows. No-one cares, and now I can't even..? And it's my one day off and I'm covered in unicorn entrails. I hate my life. I actually hate my life. You should have let them have me."

Merlin collapsed in defeat, and Edward ruffled his hair.

"On the upside you have a lovely singing voice," he said, and Merlin groaned his loathing of the universe into the unicorn-splattered ground, and vowed that the next time a total stranger showed up in his bedroom on a Sunday morning, he'd just pull the pillow over his head and pretend to be asleep.

A/N: Thank you for reading. Reviewers get Merlin, Edward or Gaius to sing them a ballad of their choosing.