Two and a half months earlier...
Arthur, half of the way down to the training field, slowed to a stop. "Oh, come on," he said to himself, poking at his empty scabbard. Merlin must have forgotten to put the sword back in its place after cleaning it again. Rolling his eyes, he turned around and went back towards the way he came.
Arthur pushed open the heavy door, and stopped at the sight of Merlin cleaning his chambers. Or, rather, he was stopped by the sight of Merlin flicking his hands around while Arthur's chambers cleaned themselves. His back was to Arthur all of the while, and as a result he didn't see the prince standing there. Watching Merlin. Using magic. Merlin was using magic.
And, all the while he was doing this, Merlin was humming. Humming. Humming some nonsensical, tuneless, Merlin-like melody as he sent boots running off against their will and dust crawling out the window. He stopped, surveying the now clean room. Arthur's hand went for his sword, just to remember the very reason that he'd come back here was to get his sword. Merlin started to turn towards the door, but Arthur moved away, pressing himself into hiding out of sight.
Merlin poked his head out the door, looking around warily. Arthur didn't even dare breathe as Merlin vanished back into the room for a moment. Then, whistling beneath his breath, his servant bounced out of the room and down the hall, still humming that odd tuneless song.
Arthur left his alcove and, as his first action, proceeded to tear apart his room searching for any signs of magical threats. It wasn't long before his room was trashed, belongings spread out all over the floor and a pair of pants dangling off of the curtain rod. Arthur stood in the middle of the disaster, staring blankly into space. Some sort of dangerous magical creature had, obviously, kidnapped Merlin and proceeded to take his place in the castle with no doubt nefarious intentions. At least, Arthur hoped the idiot had only been kidnapped. The alternative was...unsettling. Scratching his head, he considered his options.
Any other time, Arthur would have gone straight to Gaius, but Gaius wasn't here, not for another week, at least. And if he went to his father, then Uther would just have Clearly-Not-Merlin executed, leaving Arthur with no way to track down Real Merlin.
Nodding to himself, Arthur walked off in the direction Clearly-Not-Merlin had set obliviously off in, completely disregarding training. Before he went to the knights, though, he wanted proof and a solid argument.
It was two days later, and they were to leave on patrol the next day. Arthur sank down on the side of his bed. Two days, he had spent the last two days following Merlin everywhere the servant went. He had assigned him ridiculous, impossible tasks, and with grumbling Merlin would complete them, each time using magic. He'd also spoken to Gwaine and Lancelot and the others, but none of them had noticed anything out of the usual about Merlin. And the more Arthur thought about it, the more he came to suspect that Merlin hadn't been replaced by a dangerous magical creature, but was actually a dangerous magical creature himself.
A sorcerer.
Arthur buried his face in his hands. The last time he'd been this stupidly terrified was when he thought that Guinevere was going to be burned on accusations of witchcraft. Like Merlin would be if he were caught.
Arthur didn't think for a second that Merlin would try and hurt Camelot. Maybe he'd come to the city with such intentions initially, but Arthur couldn't be bothered to care at this point. He refused to believe that the Merlin he knew, the only one who had dared to just tell him to his face what he thought, could do anything to remotely attack Arthur. If he was going to, surely it would have happened by now.
But that didn't change the fact that Merlin was a sorcerer. In Camelot. He was actively using and practicing magic within not only the kingdom, not only the city, but right inside the castle walls. Merlin was not safe. Merlin, smiling and stupid, lying and deceiving, was not safe here.
