It starts with one man. A butcher at the edge of town, discovered dead in his home, half rotted already even though he was seen alive the day before.
Next is a woman, a baker, found in her kitchen. Another man, another woman, and then a groomsman in the castle stables. All of them rotting too soon, and Gaius has judged that the rot began before they died. Merlin is not ashamed to be among those who had to step away and be sick at the news.
Arthur watches the surge of magic, terrible magic, tracing a line through his people straight to his door and his every aspect is grim, furious.
Merlin is too busy to comfort him, scouring his tomes, questioning Gaius until he is exiled from their rooms, even calling Kilgharrah in search of answers. There is nothing.
No one has heard of this magic. No one knows it, no one's seen it, no one can even speculate on its origins or possible countermeasures. It goes against every law of magic they know, to bring death to a body while it still houses a living spirit.
Desperate, Merlin begins trying scrying spells, spells for truth and clear sight, anything that might lead him to the sorcerer or to useful answers. All he ends up doing is trapping himself with a spell that lets him speak truth, the whole truth, and nothing but from sunrise until sunset.
So of course, Arthur calls for a meeting with the knights and his court that day at lunch and insists Merlin remain to attend - suffer - him.
It's hardly a meeting; a bloodletting, really, as Arthur and his men go in circles venting their frustrations and arguing that more must be done when they have done all they can and nothing works. They do not have the manpower to guard each individual citizen and even if they did, no one sees this sorcerer do their work. It's as if they're a ghost passing through walls straight into the victim's bedchambers.
Merlin's eyes close at that thought and he considers - but no, magic is a gift of the living. Artifacts may store power, but they cannot act and if this were an artifact, someone would have heard of it.
He sighs, careful to keep it quiet. Only six hours left until sunset, and he's been restricting himself to banal small talk or speechlessness as much as possible specifically to avoid any questions he can't afford to answer truthfully. It's exhausting, but it's almost done and once this meeting is over he can hide out in his room and try once again to scry out this enemy.
Merlin rises from his thoughts abruptly, realizing the room has gone silent. Then he sees it, layers of shadow coalescing at the center of the hall, settling into the shape of a man. The longer he watches, the clearer the figure becomes: a beak of a nose, pale skin damp with sweat, hair long and lank, eyes wide and dark as a caught fish. The reek of fresh rot drifts from the man, the sorcerer, as if in warning.
No one has to ask who he is.
Merlin glances - Arthur is two steps ahead of him, rising from his throne in alarm. The invading sorcerer has eyes only for him, sallow lips stretching in a vicious smile. The knights and the court are drawing weapons, shouting, and that rot smell grows ever stronger as Merlin's thoughts begin to race.
The world is so loud Arthur is in danger there are so many lies Merlin cannot protect him in such a public place that terrible rotting spell is spitting from the sorcerer's lips he is pointing at Arthur Merlin cannot even make himself open his mouth he cannot hide this Arthur is in danger Arthur will die Arthur will die Arthur will die.
The spell will not let him speak less than a whole truth.
Merlin raises his hand. His shoulders slide back, down. Most are too caught up in the chaos to see, but Arthur had turned, sought out his servant in a glance and he watches Merlin's mobile face go smooth like glass, hard as stone, resigned and unforgiving.
Arthur sees his eyes flare gold.
"You will be silent," Merlin does not shout, but he is heard. The sorcerer's mouth closes mid-word. The room quiets.
The sorcerer's stunned expression quickly twists with thwarted rage and he lunges for Arthur, seizing the moment of the court's shock. Merlin does not move.
"You will be still."
His voice is still even, his raised hand steady on his wrist.
The sorcerer drops to his knees, his limbs seemingly locking in place, and only then does Merlin step forward. He ignores the sick, gaping stares of his unwanted audience. His face is still uncharacteristically blank, but as he steps past the throne, Arthur finally sees the fury in his blazing gold eyes and the rigid line of his shoulders.
Arthur has seen Merlin cry. He has seen him exhausted and frustrated and joyous and in pain, but suddenly he realizes he had never before seen Merlin angry. Not like this. His servant is a sorcerer. His friend is a sorcerer. Merlin is -
Merlin is looking at him, a hasty sideways glance but Arthur has not taken his eyes from him and he catches it. Staggered, Arthur finds he can't quite draw a breath. Merlin is furious, yes, but with that look Arthur remembered that he knows his friend and only slightly behind the fury is terror, the sort of blind terror Arthur has seen in trapped deer at the sight of a hunter, has seen in the eyes of condemned men being dragged to -
No. Not Merlin. Merlin should never look like that, should never look at him like that, like he is - is waiting to die on Arthur's word. Like he had been waiting all his life.
Merlin is less than three steps from the sorcerer when he stops. He tells himself to forget that Arthur is watching, that Gaius and Gwen and Leon and Gwaine and none of that matters. He fills his mind with the horrific deaths he has seen this week, the vicious, terrible purpose this man has turned magic to satisfying.
It feels like a violation. Magic has been turned on Camelot in many violent forms and Merlin has never liked it, but this rotting spell had not been used to achieve any definition of balance, had not even pretended to excuse its disgusting purpose: to cause pain in the innocent, to stain even the souls of those who must witness the aftermath.
The fury feels like it is burning him alive. Or maybe that's the magic, finally fed up with shrinking inside him.
"Who am I?" Merlin barely recognizes his own voice. It feels like fire will burst from his skin any moment and something awful must be in his face because the violator is finally looking frightened. His next words are hissed out, "You will answer me."
The sorcerer's whisper echoes, "Emrys."
Merlin does not pause for the gasps, barely hears anything but this disgusting creature's voice anymore.
"What is Emrys?"
"He is prophesied to protect the Once and Future King," the sorcerer stutters, "he is said to be the greatest wielder of magic that ever has or ever will be."
Merlin's mouth stretches in something that might have been a smile on another day.
"The Druids compare Emrys to water and fire and earth and air, their songs and poems are eloquent about his power, but they have never called him a 'wielder of magic.' Do you know why?"
The sorcerer's mouth opens and closes silently and Merlin leans in, "Because they know I am magic. And you are a violation of everything that I am."
"Others have come. Others have threatened what is mine to protect, but never did I consider this course of action. You have turned magic to creating the most despicable, pointless horror I have yet to know and it is intolerable to me that you continue to exist within my power."
Merlin watched the sorcerer's pupils dilate in panic and felt nothing - not satisfaction, not guilt. He could not stand for this creature to interact with him in any way ever again and that was a truth that required no consideration.
"Magic is a gift," Merlin murmured. "Like water or fire, earth or air, magic is a necessary element in every living thing whether they use it or not. Yet air can be taken from you, water, fire, earth, anyone can deprive another person of these elements. The world has never been deprived of magic, there has never been enough cause, but you - you do not deserve my gift."
Merlin pressed his palm into the sorcerer's forehead, reaching in some way he could never describe...and took the magic back. Without word or fanfare, he yanked at the root of magic in the sorcerer and tore free every shred of capacity for touching the wellspring of his power.
The once sorcerer withered, like a dying flower. Merlin watched as his form curled and shrank and went still.
Then, perhaps because all his emotional human excesses seemed to seep back in at once or perhaps because there was no longer any point in hiding or hoping, Merlin opened his mouth and let his voice roll out through the lands of Camelot and beyond, asking from every breath of air and blade of grass, "Would anyone else like to threaten my king?"
After, he had time to notice a glow rising off his skin and blink confusedly down at his arms. Turning to meet Arthur's wide eyes, he promptly collapsed into blissful unconsciousness.