Somewhat crack-ish, Merlin/Arthur implied, spoilers for season 1.
Disclaimer: I don't own BBC's Merlin.
Sceptics
Out of all the reactions Merlin may have expected Arthur to have to the "I've been talking to the dragon under the castle"-thing – anger, sympathy, even indifference, considering how the "I'm a warlock" went over with no more than a moment of shock, a shrug, and a passive-aggressive list of chores he can't do in his room – insane laugher wasn't one of them.
"I don't see what's so funny about it," he complains, after Arthur has stopped, given him a look from where he's standing, and started laughing again for the third time; Merlin is tempted to just stand up and leave him there, but Arthur's brought them to a sunny clearing in the forest where they're safe from Camelot's ears, and Merlin isn't entirely sure he'd find the way back on his own.
"It's..." Arthur tries to catch his breath, and makes a courageous attempt to sound serious for a moment. "I'm sorry for the thing with your mother, I am, but –" another burst of laughing. "– it told you we were destined for each other! That we would be by each other's side forever! And you bought all of it!"
"It didn't put it like that," Merlin snaps, seriously mollified by now, and picks at a tuft of grass.
"No wonder you kept following me around. Did it say we were going to get married and unite Albion together as well?" Arthur asks gleefully.
"No," Merlin says hastily, and he can feel himself blushing.
"It did, didn't it?" Arthur says, watching him, and he's calmed down enough for the laughter to make place to an amused smirk; Merlin finds that he doesn't like the change, and he can feel his blush getting worse.
"It didn't say anything about us getting married," he mutters angrily; he's aware that by that he admits to the rest, but it can't get much worse.
"Maybe it was saving it," Arthur offers, and comes close enough to ruffle his hair. "We could go and ask."
Merlin brushes his hand off and crosses his arms.
"I don't see how I should have guessed," he snaps, a little sulkily.
"Merlin," Arthur says in that falsely kind voice he uses for announcement like "I have decided to help you with the mace-practice you clearly need" or "they've designed a new livery for the servants of Camelot, do you want to see it" or "we'll go under the cover of hunting" (Merlin fails to see how it's necessary for their cover that he carries the arrows, Arthur's sword, and the rabbit carcasses the whole way), and squatters down in front of him. "Sometimes there are fairs here in Camelot and elsewhere, and sometimes, at the fairs, there are fortune-tellers."
Merlin shudders.
"And sometimes you find them and cut their head off?" he asks.
"No, we make them pay a fine for fraudulent practice," Arthur says dryly. "Mostly, they tell everyone they will become rich and successful. And that they'll marry me," he adds, with a self-satisfied grin. "You have no idea how often I've been told it's my destiny to be with some barmaid I've –"
"Stop bragging," Merlin cuts off, rather sharply; Arthur gives him an odd look and actually does.
"And then they add that they shouldn't tell anyone about this, and to remember them when they've reached their promised high. And no-one falls for it, except some twelve years old girls. And you," he concludes, with relish, and stands up.
"So first you let them settle and later you take their money," Merlin asks, after a short silence.
Arthur crosses his arms.
"You're missing the point here. Which is that you're an idiot. And a girl."
"I was told by a dragon, not a fraud who says this to everyone!"
"How would you know?" Arthur asks, grinning infuriatingly again. "Maybe it talks to everyone all the time!"
"But you don't know," Merlin points out. "We don't even know for sure that what he said to me isn't true either."
"Pity it never mentioned our marriage then," Arthur says. "And actually –" He pauses, then actually sits down in the grass next to him and says quietly but with emphasis: "I'm not supposed to know this, so you will swear not to tell Morgana." Merlin nods his agreement, despite his current annoyance with Arthur: Morgana is a force one needs solid alliances against; not that he won't tease Arthur about this later. "It told Gwen that she was going to be queen one day."
He leans back, hands in the grass to brace himself, and looks triumphant. Merlin winces. That – doesn't sound likely.
"It's not impossible," he says, without much faith; maybe some passing king will see her and want to marry her, she's certainly likeable enough, though Merlin doesn't think that enters into it; or maybe it will turn out she's someone's long lost heir.
Arthur rolls his eyes.
"Yeah, maybe, but he probably said the same to half the girls in Camelot."
Merlin picks at a grass tuff again, looking down.
"And he says the same to all the warlocks?"
Arthur sighs, and his voice is a little more serious when he says:
"There are no warlocks in Camelot."
"How do you know? They could be hiding."
"Yes, probably, they would. Because they're not idiots who draw attention to themselves because some underground voice tells them to," Arthur says, almost kindly, and puts a hand on his shoulder, and it sounds like a compliment or maybe a "thank you" when he adds: "That's just you."
Merlin can't help smiling at him.
"I still think it's telling the truth," he remarks, after a silence.
"Mm-hm," Arthur says, and smiles back. "Coincidence."