"You truly never do as you're told, do you?" Arthur asks, arms folded across his chest as he surveys his pathetic excuse for a manservant, sitting on a bench in Gaius's chambers instead of attending to his duties as he should be.

The young man glares at him unrepentantly, turning an unkind eye on the soldiers who are looking through the physician's chambers as well, examining the room for evidence of sorcery. Though he would never admit it, Arthur believes it's a waste of time to search here as well, that there are other, more useful places to start looking for the cause of this sickness. His father isn't inclined to listen to such things, however, not after hearing the word 'magic.'

He looks to Gaius, trying not to stare at the still form beneath a winding sheet on the examination table. "How long until you have found an answer for this?" he asks, eyeing the marble-white hand veined in ghostly blue dangling over the edge of the table.

"That depends on how many interruptions we have," Hunith replies, then turns and impatiently brushes aside the hand of a soldier rummaging through bottles. "Have a care with those! They are dangerous if handled incorrectly."

"Be cautious," Arthur orders sternly. He remembers the first lesson he'd ever learned visiting the physician's chambers—to never touch anything unless explicitly told to do so. He still has a faint burn scar on his wrist from the first and only time he'd disobeyed that rule. "We're done here," he calls to the soldiers when he sees Gaius flinch at another stack of books being overturned. "They'll hardly find a cure for this if we set this place to ruin. Out, all of you. Merlin, with me."

The young man scowls, straightening up a scattered stack of parchments. "I'm well occupied here."

"Now!"

"Oh, alright." Merlin turns and embraces Hunith, bending slightly to kiss her cheek. "I'll return later, Mother. Let me know if you need anything," he says, then turns to Arthur. "Very well, sire, let's go."

As they stride down the corridor, the soldiers following behind them, Arthur casts a sideways glance at his manservant. "Mother?" he repeats.

Merlin gives him a look as though he's just looked up at the sky and asked if it was blue. "Yes. Hunith is my mother." The corner of his mouth twitches up. "Did you not know?"

They stop outside another set of chambers, and he sends the soldiers to inside to search it. Arthur folds his arms across his chest. "I knew Hunith had a son, I didn't realise it was you," he replies shortly, then throws a narrow-eyed look at him. "Why were you even there anyways? You're meant to be staying out of trouble and attending your duties. Haven't we gone over this already?"

The young man mimics his posture, narrowing his eyes right back. "Mother asked me there to look at the victims. I thought that took precedence over your laundry, sire."

"Why you?"

"Because I know somewhat about medicine, and fresh eyes can notice different things."

Arthur hums. "And have you?"

Merlin frowns and shakes his head, brows knitting together. "No. Some of them have never met, don't even live near each other, so it's hard to find how they could have gotten sick," he mutters. "Not to mention the lower town isn't exactly an organised place, so anything could have—"

He cuts off sharply as two men come around the corner carrying a woman's body on a stretcher, bound for Gaius's chambers. The woman, however, isn't a peasant, wearing a rich gown and jewelry. A courtier.

"That…is not good," he mutters.

"What? What's wrong?"

Merlin takes Arthur by the arm and pulls him aside into one of the alcoves, lowering his voice; the King had warned them not to start a panic. "We've been assuming that the sickness is sourced in the lower town, but if courtiers are getting ill, then that means it's something else."

The prince scowls. "How do you know that?"

"Think! How many courtiers do you know that visit the lower towns in the midst of an outbreak? That means it isn't spread through contact. They're hardly breathing the same air, and they're certainly not eating the same foods, and…" His face goes white, eyes widening.

"What? What is it?" Arthur hisses, grabbing his shoulder.

"Water. It's in the water." He twists out of Arthur's grip and sprints down the corridor.

With a muttered curse, Arthur takes off after him. He might be a lazy clout, but he can run like a deer, long legs taking the stairs almost three at a time. "Damn it, Merlin, slow down before you knock someone over!" he snaps, rounding a corner and seeing a serving girl pressed to the wall, wide-eyed and startled at their passing.

The manservant doesn't slow down until he reaches the pump. He'd snatched a vase from somewhere, probably from a passing maid. Without ceremony, he turns it upside down, dumping the flowers on the cobblestones, and fills it with water, his face drawn. "Please be wrong," he murmurs. "Arthur, is there any other water in the city? That doesn't come from the aquifer?"

"Yes, some, in the emergency stores." Not enough, his mind whispers. Not enough for the entire city, not for long. Arthur stares into his sharp-boned face, a knot forming in the pit of his belly. "You don't truly believe this is in the water?"

Merlin gazes down into the vase, holding it carefully between his hands. "I devoutly hope not, but I scarce see how it could be anything else. Come on, I need to get this to Gaius and Mother."

Arthur feels as though he might be sick, though hopefully not in the life-threatening way, on the walk back to the physician's chambers, staring at the vase in Merlin's hands. Not the water. Please not the water. If a sorcerer truly wanted to strike at Camelot, they could not have chosen a better vein of attack. He thinks of all the people in the city, the castle, relying on the water from the aquifer, and swallows hard.

The courtier's body is already laid out on the table when they arrive in Gaius's chambers. Hunith is examining her as Gaius makes notes upon a piece of parchment. "What is it, little bird?" she asks without looking up.

"I believe I know the cause of this sickness, Mother," Merlin replies quietly. "The water, from the city wells."

Both heads turn towards them quickly; Arthur hates the grim lines in their faces. Hunith pours a measure of water from the vase into a clean glass, holds it up to the light to inspect it, then turns and pulls a sprig of lilac from a bundle of fresh-plucked herbs and flowers. "I pray you're wrong, my boy," she murmurs, gently pushing the flowers down into the water, submerging them entirely.

"If this is in the water, if that is how this is spread, is there any way to stop it?" Arthur asks of Gaius. "A way to cleanse the water somehow? Boil away the impurities, anything?"

The old man spreads his hands. "It would require study to find out, sire. There are many kinds of malignant magic, and each one is different from the next. However, if the sickness kills so quickly, then it is the work of a very powerful sorcerer. Nothing could remove it from the water but to eliminate it at the source."

"The sorcerer?" he hazards.

"Perhaps. Some kinds of magic can be wrought separate from the self, given life of their own. Executing the one responsible might not break the enchantment at all."

"Maiden's mercy."

Arthur turns at Merlin's quiet exclamation and moves closer, the knot in his stomach growing heavier. The sprig of flowers they had stuck in the water has gone entirely white, even the stem of it, the petals milky and translucent, veined with spidery blue lines. "Gaius," he says quietly. "Take that and come to the council chambers. We need to tell my father."

Apparently, the fates have not only seen it fit to bestow an entirely useless manservant upon Arthur, they've given him a suicidal one as well.

Arthur doesn't believe that Guinevere is the source of any enchantment. If there was a single person in Camelot upon whose goodness he'd wager his own life on, it would be Guinevere. He doesn't believe she used magic to heal her father, either. He has never been much good at dissembling, but he knows the nine tell-tales of a lie and the game of faces is one he plays well. She truly does not know how her father came to be healed, only that he was. The real trick of it is to convince his father of the same truth. Uther scarce listens to reason once magic is involved, but the right words can bring him down to a more manageable temper. Morgana only serves to provoke him most days, especially once she gets more indignation in her than sense. Which means the task falls to Arthur.

He very nearly has it when that thrice-damned Merlin undoes it all in a single stroke, flinging himself into the council chamber and proclaiming himself a sorcerer.

In any other situation, Arthur might have called it admirable, doing something so foolhardy for the sake of a friend. Now he just wants to wring the little wretch's neck.

Instead he lies. Not very well—there is a reason he writes his speeches ahead of time—but well enough that his father believes it. Arthur would be hard pressed to even say why he bothered. A part of him would like to say it is only because Leon is a close friend and would never forgive the execution of his half-brother. That's not the entirety of it, surely, but it's all Arthur can bear to admit at the moment. So he digs his fingers into Merlin's shoulder hard enough to bruise and silently wills the idiot not to speak, smiling with all his teeth and forcing the words out.

There's a horrible moment of silence, but then for a miracle, the King chuckles and makes amusement of it. Arthur lets his breath out slowly; fools had been sent to the whipping post for less. Keeping his grip firm, he steers Merlin towards the doors and lowers his voice to a hiss, loud enough for only the two of them to hear. "I am struggling to keep him from sending Guinevere to the pyre as it is, I do not need you mucking about making it worse. Now get out." With that, he gives the young man a shove out into the corridor; Merlin throws him a positively mutinous glare, looking as though he means to charge right back into the council chambers and knock the prince over to do so.

He might very well have done it, if not for Leon. The knight strides up and catches him none-too-gently by the scruff of the neck, yanking him back a step as if bringing a lymer to heel. "I'll take him, sire," Leon grits out. "You needn't worry about being interrupted again."

"Good. I expect you to attend in my chambers when this is over, Merlin," Arthur orders but gets no further before the tall knight turns about and strides away, hauling along his half-brother. He almost pities the idiot.

Leon twists a hand in the back of Merlin's scarf, dragging him down the hall and well away from the King's council. He flings open a door and finds a chamber empty but for a servant cleaning the windows. "Out!" he barks sharply, and the servant bolts like a startled rabbit. He shoves Merlin inside and slams the door shut so hard it rattles the hinges. "Have you completely lost your mind? What in the seven hells were you thinking?" he thunders.

"I was trying to help!" Merlin shouts back, rubbing at his neck indignantly.

"No, you were being a fool!"

"I could not sit there and do nothing while people are dying! Not when I could do something about it!"

"Name of the Mother, Merlin, you cannot be this reckless!"

"I am not a child! My choices are my own, you cannot make them for me!"

"It isn't just you!" Leon shouts, shaking him by the shoulders so hard his teeth rattle. "If you were found guilty of sorcery, do you think the King wouldn't suspect me? Or Mother and Father? Hunith? Gaius, even? If a sorcerer were to be found in the royal employ, then not a single one of us would escape his suspicion. Guilty or not, he would line us up on the block just to make himself feel better for being played a fool!"

"I'm sorry!" Merlin shouts back, then presses a hand over his mouth, guilt coiling in the pit of his belly. He forces a hitching breath, a stinging in his eyes. "I'm sorry," he repeats softly.

Ire vanishing, Leon folds his arms around him, pulling him in close; Merlin buries his head against the taller man's shoulder. "It's alright. Shh," he murmurs, resting a hand atop Merlin's head. "I love you too much to lose you, little brother. I don't think I could ever bear it."

He nods into the knight's shoulder. "I couldn't just do nothing. I didn't want her to lose her father," he whispers hoarsely.

"I know. I know." Leon runs a hand across his hair. "It's harder to bear the suffering of others than it is to bear your own. But as strong as you are, Merlin, you can't save everyone. Children lose their parents eventually, and there's nothing to be done about that." He gently grasps the young man's shoulders and gently pushes him back, holding him at arms' length. "But what we can do now is to find whatever it is that's doing this and stop it before anyone else dies."

Merlin nods shakily, using the edge of his neckerchief to dry his eyes. He stares up at his brother, jaw getting that obstinate set again. "I won't let Gwen burn."

"How else can we explain Tom recovering, then?" Leon runs a hand back through his hair, pacing across the chamber. Abruptly, he stops. A smile starts to form on his face. He turns to Merlin. "I have an idea."

"Iron?"

Arthur picks up the piece of ore, turning it over in his hands curiously.

"Yes, sire." Standing before the prince in his chambers, Leon doesn't have to force a note of annoyance into his tone when he explains, "I didn't want Merlin causing a spectacle in another ill-thought attempt to rescue Guinevere, so I thought to look into it myself. Cold iron can bind a sorcerer from their magic, but it can drive away harmful magic in almost any form. As the blacksmith for the lower town, Tom is surrounded by it constantly, even breathes it in the forge. I don't believe that he was healed by magic, sire, I believe the magic was repelled from him."

The prince leans back against his desk and gazes at the ore in his hand. His other hand toys idly with the amulet around his neck, rolling the pendant between his fingers. "Iron. Of course. Do you think it might keep others from becoming ill if we were to distribute it amongst the people?"

Leon spreads his hands. "I don't know, sire. Gaius and Hunith both agree that this magic is the work of a very powerful sorcerer. Who knows how much it would take to protect every person? No, sire, I believe the only thing for it is to destroy the sickness at its source."

Arthur's gaze sharpens, turning the ore over in his hands. "In the aquifer. It must be in the aquifer. That's where the wells all draw their water from." With the search for the sorcerer continuing to yield no results, he suspects they have long-fled and left only their work behind, as Gaius had said. A magic that has taken on a life of its own, separate from its caster. Nodding, he straightens up. "Leon, go down to the dungeons, stay with Guinevere, don't let the guards take her anywhere, and if you see Merlin, tell him to get my sword and meet me outside the council chambers. I'm going to speak to my father about this, see if perhaps he will see reason."

"Yes, sire."

Arthur swears aloud when he rounds the corner and collides full-on with his manservant, staggering back half a step from the impact. "Seven hells, Merlin, what are you doing? Where have you been?" he demands, grabbing the boy by that silly neckerchief of his.

"I know what it is," Merlin replies breathlessly, as though he's sprinted the entire way and grinning like a fool.

"What what is?"

"The source of the sickness." It's then Arthur notices that the other man's carrying a book in his hands. Merlin flips it open and rifles through the pages quickly, then turns it around to show him the illustration of a strange, misshapen beast with a mouth full of very sharp-looking teeth. "It's called an afanc. It is a beast formed of clay and brought to life in water using magic. Whatever it lives in stagnates and festers."

"Huh. I'm impressed. If it lives in water, then it has to be in the aquifer. I'm going down there as soon as I speak to my father, so go and fetch my sword and—"

"You can't kill it with a sword."

Arthur blinks. "What?"

"It's an elemental. It was made with water and earth, so in order to unmake it, you will have to use fire and air. Your sword will be of no use, you'll need a torch."

"A torch." He lifts a hand to pinch the bridge of his nose, forcing a deep breath. "I am expected to kill this…afanc, as you say, with a torch."

Merlin closes the book and tucks it under his arm. "Yes. I'll help you."

How wonderful. "Very well, we'll go and see my father and—"

"Arthur, we can't wait," the young man protests, interrupting him. "This creature grows more powerful the longer it is left down there, and the more the sickness will spread. If we tell your father, it will just be a waste of time. You and I can handle this."

He arches an eyebrow, staring at him. "You are aware that I could have you beaten for speaking to me thusly?"

Merlin shrugs. "I'm certain you could, sire. Do you have keys to the aquifer?"

"Of course I do."

"Then let's go."

Arthur stares after him in disbelief, shaking his head. How this coltish lad has managed to live this long without being laid out…. He strongly imagines that Leon has something to do with that. Unhooking the keys from his belt, he follows after his manservant, musing on the knowledge that it should be the other way around.

The aquifer is a part of the natural caverns that lie beneath the city and are therefore dark and quiet, broken only by the faint dripping of water and the distant scuttling of vermin. The path to the aquifer itself is lit by staggered torches, and Arthur moves further into the cavern holding one out in front of him, wishing deeply that he had his sword with him. Useless or not, he would have felt better with it.

Merlin follows close behind him, holding a torch of his own aloft. Truly, Arthur hadn't expected the servant to follow him, but the fool boy did. He's braver than he looks; granted, he does look like an idiot.

"Here." They come up to the deep pool at the edge, the waters deceptively calm, a thin sheet of wispy fog swirling over the surface. Arthur crouches on his heels to study the soft earth but sees no tracks aside from the faint, smudged footprints of whomever was last down here, however long ago. "I see no spoor. Are you certain of this?"

"It will be in the water, Arthur. We have to lure it out," Merlin replies. "Fire and air. It must be out in the open." Without a moment's pause, he peers about, picks up a stone from the ground, and walks up to the edge. He cocks his arm back and hurls the stone into the water.

"Merlin!" he hisses, glaring at the young man.

"What? We can hardly do any vanquishing if we stand here looking at nothing." Merlin picks up another stone and throws it; the splash of it landing is remarkably loud in the stillness of the caverns.

"I hardly see how this is going to help—"

The surface of the water breaks as a dark shape surges up out of the pool, an enormous, misshapen jaw open wide in a gurgling roar. Arthur grabs hold of Merlin's jacket and hauls him away from the water, brandishing his torch at the afanc.

The creature crawls up out of the pool, growling with a sound like rushing water underground. It moves on all fours, loping and awkward, and it has no eyes that Arthur can see at all, only a yawning jaw that could swallow a man's head whole. The smell of it makes Arthur gag, covering his mouth and nose with his sleeve. Like stagnant water and rotting vegetation, putrid and rank. He swings his torch at its head; the afanc roars and swings one huge claw at him. He brandishes the torch again…and meets only empty air.

"Where did it go? Where is it?" he barks.

"I don't know." Merlin's hand clenches around his jacket. "Stay near, we can't let it separate us."

Arthur turns in a slow circle, holding the torch out before him. "Do you see it?"

"No."

He turns again and takes a startled leap backwards scarcely in time to avoid the swipe of the afanc's claws. For something so large and misshapen, it is uncannily agile. Beside him, Merlin swears an impressive streak, swinging his torch at its head, and it lashes at him as well, sending him leaping aside. When Arthur tries to land another blow against it, the beast shies away and is in the next instant gone again.

"Name of the Mother, how does it do that?" Merlin mutters from behind him, swearing quietly.

Arthur ignores him, trying to listen for any sound of it, the shuffle and scrape of claws on the ground, the dripping of water, and hears nothing but their own ragged breathing and the crackle of the torches. The rank smell is everywhere, permeating the air. Aware of Merlin's shuffling footsteps behind him, he turns.

The afanc rears up between them with a roar, lunging towards him.

On startled reflex, Arthur shoves the torch into its open mouth.

He might as well have thrown a lit taper into a dish of lamp oil. The creature's bellow turns into a shrill shriek as it rears back, twisting and thrashing; flame courses over its hide, consuming it entirely. It spits and hisses and stinks like a wet coal, pungent steam filling the air. When the fumes clear, the noise dying into silence, there's nothing left of the afanc except a handful charred black clay, crumbling to the touch.

Stunned, Arthur looks over at Merlin. The young man's still holding his torch, an expression of awed glee on his face as he stares at the ruins of the afanc. He laughs aloud despite himself, brushing the greasy soot from his hands. "Come on. I need to tell my father. Guinevere's been sitting in the dungeons long enough." As they make their way back up to the surface, he glances over and laughs a little. Merlin's face is smudged with soot and dust, no doubt from being too close to the burning afanc, and Arthur's certain he looks no better. "It near pains me to admit it, Merlin, but I must admit you have done...very well today," he says, then catches his arm. "Do me a kindness, though."

Merlin arches his eyebrows a little warily. "Oh?"

"Don't ever admit to sorcery again."