It's been days and Arthur still cannot let it go. The words revolve in his head, every time he closes his eyes. They bother him and he can’t stop bringing them up.
"You heard what Gaius said, right? About the unicorn?"
"Really? I didn't hear any such thing."
"I was wondering. Why you? Why not the others? My knights. Or me?”
"I think you've answered your own question there, sire."
"What? Merlin! I swear, sometimes I don't understand a single thing that comes out of your mouth!"
"The creature shows itself to the pure of heart. Is that why it only showed itself to you?"
"Is that so hard to believe?"
"By the gods! You're a virgin, aren't you?"
"No, I'm not!"
That was two days ago. Since then, Arthur's been subjected to questionable stew, outrageously dyed shirts, missing belts, being woken up rather aggressively and the occasional slice of stale bread.
Oh, and Merlin being skittish and refusing to meet his eyes.
It's been absolute hell and not just because Arthur's pants are unusually tight at the front.
So, when he sees Merlin this morning, whistling his way out of the kitchens and passing Morgana's chambers, something inside him snaps.
There’s a tussle. The soubd of broken crockery. And then they are in a tiny broom cupboard, dark and stuffy with dust motes glittering in the light penetrating through the gaps.
Merlin's pinned, face to the door, arm twisted impossibly behind his back, clutching weakly at Arthur's jacket, trying to pull him close. Arthur’s uncomfortably hard, and as he brushes experimentally against Merlin's little bottom—so good.
Merlin struggles and writhes, outright moaning, "Arthur..."
That's all the assent Arthur needs before he’s panting and grinding against Merlin's butt in earnest.
Finding Merlin's other arm, he pins it above his head. He nips Merlin's ear. Speaks, voice hoarse. "Tell me, Merlin, you ever had another man's cock up your arse?"
"No..." Another moan and Arthur can’t help himself. "You wouldn’t be so pure then."
"Don't — ungh." Merlin says, rutting against the door. "Don't. Stop."
"I'll fuck you. Fuck you in that forest where you found the Unicorn. Fuck you through the ground. Tell me, do you want it?"
"Yes, yes, yes. Please don't stop."
A shock of pleasure runs up Arthur’s nerves, and then it’s over. He spills in his breeches and goes loose-limbed before regaining his breath and pulling back.
Merlin isn’t faring any better, slumped against the door, breathing hard. Arthur sends a little thanks to the Gods that the door didn't unlatch and spill them out into the corridor.
Merlin turns around to face Arthur. "Gods, you're such a prat."
Arthur huffs, trying to hold back his laughter. This, right here, is Merlin: totally insufferable, with the biggest, purest heart in all of Camelot. Probably why the unicorn chose him.
Suddenly, it doesn't feel like a big deal anymore.
"Ah, I hate you so much. I can't believe you made me do this in a dirty cupboard." Merlin winces as he puts his clothes to rights, but then smiles, eyes shining in the slanting rays of sunlight.
Arthur laughs, privately. Perhaps the unicorn was right after all.