A/N: What can I say? This is pure fun. Got the idea from someone else, so I can't take all the credit. Several people have done something akin to this before, but hopefully I can put my own spin on it, too.

Arthur liked to pretend that he knew things.

He was king, for goodness' sake. He was supposed to know things. He was supposed to be smart. Thoughtful. Wise. But as he grew older, with each passing year, more and more frequently, he began to entertain the sneaking suspicion that he didn't really know anything at all.

Of course, he continued on pretending anyway. A king couldn't be king without kingly dignity, he told himself.

Luckily, the King-Who-Knew-Naught was conveniently allied with a wellspring of wisdom to compensate for his ignorance. A helpful ally. A wise ally. An ally whom he could always count on for everything. In all, a very thoughtful, loyal, dependable ally, who was capable and powerful and trustworthy in all measures, and, among other things…

…wouldn't shut up.

He wasn't going to shut up.

Did he ever stop prattling on? Honestly.

"Merlin," Arthur intercepted whatever Merlin had been saying (something about toadspit and cosmology or some equally as absurd combination) and rounded on him in the middle of the hallway. Predictably, Merlin continued talking anyway.

"Yes, Sire?"

"Do you ever shut up?"

Merlin looked infuriatingly innocent. You're anything but, you moron, Arthur thought. A past suspicion that Merlin could read his mind recurred to the king when the Warlock smirked, as though in response to his thoughts.

"I've never found a reason to before, sire. Why do you ask?"

And although Merlin still looked just as innocent as before, Arthur glared. He could see the glimmer in those blue eyes, the smile behind that stupid, sage, sorcerer-y beard of his. Why he still kept this man around, Arthur hadn't the slightest idea.

Oh, that's right. He was wise.

Arthur briefly wondered to himself weather the word 'wise' might translate into 'annoying as hell' in the ancient druidic language of Merlin's people. It wouldn't have surprised him.

"Because you need to," Arthur said lamely. He saw the corner of Merlin's beard twitch amusedly.

"Oh, I see," His voice dripped with sarcasm. "Wise old warlock getting on your nerves again?" He was still smiling. Arthur wasn't.

"Yes."

Merlin shook his head. "Mmm. Must be annoying."

"Indeed," The king grated out.

Merlin nodded his head again, then perked up in a smile. "Well, glad I'm not him, then."

Arthur frowned. "What are you talking about?" He hated these mind games Merlin pulled on him.

"Well, I'm not old, am I?"

Wishing that that smug, smiling face would leave his memory forever, Arthur rolled his eyes to heaven and turned around. If Merlin was a sorcerer, Arthur was fairly sure that he'd pronounced some curse on Arthur so that he would have to suffer his snarkiness for eternity.

"You know, Merlin," Arthur said as they walked, "You really are an idiot."

"You said I was wise." He hovered at Arthur's ear, and Arthur tried not to look up at him. He'd always secretly resented Merlin for being taller than him.

"Well, you may be wise, but you blabber as much as a bard."

"A bard?" Merlin chuckled.

"Of course! That's all they do, isn't it? Blabber on about this and that, never shutting up."

"And I'ma bard."

"Yes."

"But a wise bard."

"Yes, a…" Arthur shrugged. It was usually Merlin who used made-up words. "A Wisebard."

Merlin cocked a speculative eyebrow at him. Arthur pretended not to see. "A wisebard." Merlin repeated. He frowned at the taste of the word. "Sounds like some sort of insect."

"Well maybe you are an insect."

"You said I was a bard."

"No, I said you were a wiseard."

"Oh, it's just 'ard', now?"

Arthur sniffed like he'd meant to leave out the 'b' sound. "Course. Like one of those stupid words you make up."

Merlin was still trying not to laugh. "I see. And, how exactly do you spell 'wiseard?" He asked, knowing the king had never been good with letters.

Arthur wished he knew things, if only so he didn't have to suffer this… wiseard. A babbling idiot annoying as hell. How would he spell that? Full of irritation and sick of Merlin's prattle, Arthur rounded on his court sorcerer and shouted,

"WIZARD!"

He hadn't meant for it to catch on, but after Arthur had called Merlin a 'wiseard' (that is, 'wizard') in public, suddenly everyone knew that Merlin was a 'wizard', and addressed him as such. Arthur hadn't planned it. Merlin hated it.

It was glorious.

"That was meant as a joke, you prat!"

Arthur kept on walking, hiding his smile. "Of course, as I'm sure were clot-pole, cabbage-head, turnip head, dollop head, and something I recall about a "bone-idle toad'. The last of which, I'll have you know, my daughter has begun to identify me by. No thanks to you, I imagine."

Merlin paused to feel proud of himself for a moment, but then they passed a serving girl, and after she curtsied to His Majesty and Wizard Merlin, Merlin frowned again. He jogged to catch up with the king.

"Prat."

"Wizard."

"Shut up."

"Why? It's what you are."

"Is not."

"Course it is. A bard-y wiseman. Suits you perfectly."

"I'm not a bard."

"No, you're a wisebard."

"Am not." Merlin insisted.

"Please. Everyone knows it's true, Merlin." He indulged in a smirk and didn't feel bad when Merlin saw it.

Merlin didn't say anything for a moment, and then, in his most determined voice,

"Well, if I'm a wizard, you're a… a…" He twisted up his mouth as he thought up something suitably insulting. "A muggle."

Arthur stopped dead in his tracks and turned to his friend with an utterly befuddled look on his face.

"A what?"

Merlin stood his ground. "You heard me," he said, wishing he could've come up with something better. "A muggle."

Arthur crossed his arms. "And what, pray tell, is a 'muggle'?"

Merlin thought. "…Someone who's not a wizard."

Arthur scoffed. "And thank God for that." He rolled his eyes and resumed walking. Merlin followed closely behind.

The pair continued down the hall together and their bickering continued until the sun went down. Neither of them could have possibly suspected the fact that in centuries to come, their insults would be immortalized in the vernacular of magical communities across the globe.

After all, as far as they were concerned, the words only meant what they'd implied: There was a babbling bard annoying as hell, and an ignorant king who had called him wise.

There was a Wizard and a Muggle.