Merlin was a sorcerer. Merlin was a sorcerer.
Arthur dropped Merlin's limp body and stumbled back, mind whited out with horror and shock. He stared at the wild mess of his chambers, the papers fluttering to the floor, the wine a dark blotch across the pale stone, like spilled blood.
Merlin was a sorcerer. Merlin lay limp on the floor, unconscious. Arthur wanted to prod Merlin with his boot to make sure he wasn't going to leap up and speak in that guttural language again, with those glowing eyes. He wanted to wail and grab Merlin and hold him close and sob apologies. What had he done? He'd only been trying to stop the magic. To stop it from coming out of him. To stop him from corrupting himself further.
Merlin was a sorcerer.
All Arthur had been able to see were those golden eyes, the light in them turning Merlin's open, familiar features into something sinister and threatening. Making them into the face of a stranger, a monster, speaking words that he had only ever heard when his life was in immediate and extreme peril. And all that nonsense before that. Had Merlin... had Merlin been using him? Had it all been a ruse, a seduction to trick Arthur into removing the ban on magic when he became king? Is that what Merlin had wanted, all this time?
He felt sick. His heart felt sick.
He had never understood what Merlin wanted. Merlin had never made any kind of sense. But he was making sense now, and it was a loathsome, dreadful sort of sense. It was every warning his father had ever given him about sorcerers, that they would lie and seduce and entrap. That magic would make any man, however good, rot away from within, so you wouldn't know of their corruption until it was too late. Arthur had not wanted to believe any of that. It had all seemed overdramatic, feverish with paranoia. But here was the proof of it.
All this time, Arthur had held Merlin like a viper to his breast. Merlin had been filled with poison, and tonight he had struck out, trying to infect Arthur in turn. And what a victory it would have been, what a revenge to corrupt the Crown Prince of Camelot, the one kingdom that stood strong against all sorcery.
And it would all make sense, except that it was Merlin. Merlin, who at some points seemed to want nothing more than to die for him. Who had cried in his arms like a child. Whose every emotion shone from his eyes, without pretense or deceit. He couldn't even keep a secret, because the moment there was an idea in his head it would be written all over his face.
Except he had kept one secret. One, but even with that, Arthur had known there was something. He couldn't have missed it, when it so obviously made Merlin unhappy not to share it. But magic?
He had not guessed it because Merlin was an innocent. Merlin was all heart and determination and exactly zero sense or forethought. Merlin was nothing like the sorcerers that had threatened his father and then himself, that sought mindless vengeance again and again. Magic was evil, and Merlin was not. Merlin could not have magic. He could not be a sorcerer.
It suddenly came to him that he had said those words before. How blind he had been, for Merlin to actually stand in front of him and his father and the whole council and announce himself to be a sorcerer, and all Arthur had thought at the time was that Merlin was being, as usual, a noble idiot, and that he needed to be saved from himself before something awful happened.
Something awful had happened.
There was a knock on the door, tentative, familiar, startling Arthur so badly that he reached for the sword that wasn't at his hip. "Arthur?" came Guinevere's voice, sounding concerned. "Merlin? Are you all right? I heard shouting. Is something wrong?"
The door was locked, thankfully. Arthur had locked it because he'd intended to have sex with Merlin to celebrate being home, to celebrate all of Merlin's secrets being out in the open. But Merlin wasn't in his bed, smiling and blushing and naked. Because Arthur had been wrong about those secrets.
"Everything's fine," Arthur said, his voice cracking.
There was a pause. "Sorry, I know sometimes you two can be, um. Right. Sorry to, um, interrupt. Um. Goodnight." Her light footsteps faded away down the hall.
Arthur breathed out with a shudder. He had to think. He had to get some kind of control over this situation, before it spun even further into madness.
He had fought sorcerers many times. He knew what magic was capable of, how destructive it could be. The sorcerers that his father arrested barely put up a fight, as their crimes rarely amounted to more than minor enchantments. But all use of magic, even the smallest of spells, was given the same punishment: death by execution, by fire or by beheading. Hanging was not enough. The body had to be violated in order to release the magic. Even a dead sorcerer was a danger until it was beheaded or burned.
Then there were the other sorcerers. The ones who weren't arrested because they were too powerful. The ones that were killed outright, without even the pretense of a trial, because they were so obviously guilty. Because they were an active threat to the kingdom, and threats had to be eliminated. Like Cedric. Like Palaemon.
What Merlin had done was far more than petty enchantments. He had manipulated fire. He had summoned some kind of wind. He had moved things without even speaking. With such crimes, Merlin had earned immediate execution. Arthur should not have strangled him, but snapped his neck and then chopped off his head. But even the thought of doing that to Merlin made him want to retch.
If he called the guards, Merlin would be dead. By morning at the very latest, because to have such sorcery at the heart of Camelot was an atrocity that his father would not tolerate.
No, what he had to do was get control over Merlin. He didn't know how bad the corruption was, how much of Merlin's soul was left to save. But there had to be something. There had to be a chance. Despite the obvious power he had wielded, despite his panicked struggles to free himself, Merlin had never so much as scratched him. That had to be important, a sign that the corruption had not yet consumed him. That enough of Merlin was left that there was a chance that Arthur could still save him. If only he'd acted sooner, instead of blindly trusting that Gaius had been teaching Merlin how to destroy magic safely.
Gaius. Arthur was going to have to deal with him, once he'd dealt with Merlin.
Arthur scooped Merlin up from the floor and carried him into the side room. He blinked as he saw that his sword, his apparently enchanted sword, was sticking out of the far wall, the end of its blade embedded into the stone. He dismissed it for now and lay Merlin down, struggling against an upswell of grief that threatened to swamp him.
Merlin looked the same as he always did. There was no malevolence in his soft features, no external sign that he was anything but himself. Arthur pulled back one eyelid and Merlin's unseeing eye was its normal blue, with no trace of gold. But he would wake up soon, and when he did, his eyes might change again.
If Merlin was too far gone, then Arthur would have to kill him. He would rather be the one to do it than let Merlin be arrested and burned. At least that way he could make it clean and quick, and whatever was left of Merlin would not suffer. But if Merlin could hold back the corruption long enough to give Arthur time to find a cure, then there was still hope.
The only way to know would be to let Merlin wake up, and Arthur could not let him wake up without taking precautions. Merlin had to be contained.
Short of time, Arthur would have to use what was at hand. He grabbed one of Merlin's ever-present kerchiefs and gagged him with it, trying not to think of how only a week ago he had performed this same action. He shied away from using his belt again, and instead grabbed the ropes from the curtains. He bound Merlin's wrists, and then his ankles and his knees, and then after further consideration he tied Merlin to the bed. He made the ropes tight, the knots solid. If Merlin could somehow still use his magic to free himself despite the gag, at least this would slow him down.
Finally, Arthur went to get his sword. It took a few hard pulls to yank it free, but then he had it. The blade was not even scratched despite being embedded in the stone. Clearly Merlin had been telling the truth about it being enchanted. But Merlin had also given him the very weapon that he needed most right now: a sword that could kill a powerful sorcerer. He had killed Palaemon with it, and if need be he would use it again. Later, he would have Guinevere fire up her forge and he would burn the magic out of it, as he had the Deorham armor.
Arthur pulled a chair over to the bed and sat down, and lay the blade of his sword across Merlin's neck, and waited.
He had been so pleased when he'd found Palaemon's ring in the pocket of Merlin's trousers, discarded as usual on the floor. It had been the one bit of proof he'd needed to finally coax Merlin into telling him the truth. It had been like pulling teeth to get Merlin to talk about what had upset him in the castle, and Arthur had been certain that the ring would provide just the short, sharp shock that Merlin needed to open up and get it all out of his system.
It was all out, now. But Arthur still had to figure out how much of that crazed mess of words was real and how much was the corruption talking.
It was not long before Merlin stirred. He coughed weakly through the gag, gave a reedy whimper, and then opened his eyes wide with horror. Though he'd barely had time to struggle, he visibly stilled as he felt the press of the blade across his neck. In the candlelight, the polished blade glinted brightly, steel and gold stark against the freshly blossoming bruises. Merlin's fingers twitched, curled into fists. Arthur waited, and when Merlin did nothing, when he did not make himself a threat, Arthur allowed himself some fraction of relief.
"Merlin," Arthur said, looking into Merlin's wide, frightened eyes. "I'm going to remove the gag so we can talk. But if you so much as think about using a spell, I will have to kill you. Do you understand?"
Merlin swallowed, the bob of his throat a slight pressure against the blade. He gave a short, shallow nod.
This was it. If Merlin was corrupted beyond all hope, he would not leave his bed alive. If not... if not, then Arthur would do whatever it took to find a cure. He had never let magic defeat him, and it would not defeat him now. If there was even the slimmest chance of victory, he would fight for it. He had defied his father and braved sorcery for Merlin before. He had no hesitation in doing it again.
Arthur leaned forward and pulled the knot open with one hand, keeping the blade firmly in place. It was the sharpest sword Arthur had ever seen, and one push by either of them would sink the blade into Merlin's throat. Merlin didn't move as the gag was pulled free. He didn't say any spells, but he didn't say anything else, either.
"Can you still speak?" Arthur asked.
"Yes," Merlin said, with barely a whisper. His voice was pained, and injured from the strangling, but there was no way to know if the anguish in his eyes was genuine or if it was a ploy.
And that was the problem. Because Arthur had no way to know what was Merlin and what was the magic. It would be difficult to separate the two without having some way of being certain that Merlin was in there at all. If he had ever been there. But Arthur couldn't believe that the Merlin he knew was just a shell, a false front behind which some monster schemed to manipulate him. Arthur knew when people were lying. He dealt with smooth-tongued liars all the time in court.
Perhaps he could arrange to have Hunith come to Camelot. If anyone would know what Merlin was like before he had been corrupted by Gaius, it was his mother. Or would she? Merlin's friend Will had been a sorcerer. Had Will corrupted Merlin when he was young? Had it started that far back?
"Arthur?" Merlin rasped, warily.
"The things I thought were your secret," Arthur began, thoughtful. "Were they true? Have you been destroying magic to protect Camelot? To save my life?"
Merlin hesitated, then said, "Yes."
"It's been you and Gaius together? He's been teaching you?"
Another hesitation. "Yes," Merlin said, but sounded less certain this time.
"I came to Camelot for help. To control my magic. Gaius was supposed to teach me. But he was... he lied to me. He used me. Him and... the dragon."
Arthur leaned closer, curious. "There's only one dragon left. My father kept him as an example. Are you actually telling me that you've been conspiring against me with the Great Dragon?"
"No!" Merlin said, clearly upset by the suggestion. "He, um, called to me, when I first arrived. He said that it was my destiny to protect you. I didn't believe him, but... then Gaius brought me to the feast, and... I saved your life. And then your father gave me to you, and... I don't know. I think... I think maybe he knew?"
Arthur blinked at him, trying to follow Merlin's leap of logic. "You think my father, Gaius, and a dragon all conspired to set you up as what, my magical bodyguard?"
Merlin looked entirely confused about the matter himself. "Maybe? All I know is that they've been lying to me about the prophecy, and--"
"Prophecy?" Arthur interrupted. He moved the blade away from Merlin's neck, because he didn't need Merlin accidentally slicing himself open. Merlin didn't seem to be trying anything, unless his baffling nonsense was supposed to be some kind of distraction tactic. But Arthur had been watching Merlin's eyes since they had opened, and there was no sign of gold.
"Yes," Merlin said, sounding slightly more certain now. "The dragon told me some of it, but I didn't know if any of what he said was true until we got to Gedref. It was written on the wall in the temple, in that room I slept in."
Arthur frowned. When they'd been hiding in wait for the army to arrive, Merlin had been going on about the cavern being some kind of old temple, about it having magic, but nothing had seemed amiss. It had been a temple, certainly, but it was long abandoned. He'd considered it safe enough when weighed against the risk of trying to find somewhere else to hide from the Deorham's patrols. Apparently he had been wrong, if some lingering magic there had worsened Merlin's condition.
"Tell it to me."
"Well, there's the first part is about fire, which I think is the Great Purge, but then it says, 'The time of magic will return. The Emrys and the once and future king will rise. And all of Albion will bow to them.' And that's us."
"I'm the Emrys and you're the, um, the once and future king?" Merlin scrunched up his face. "I don't actually know what either of those things mean, so it's not exactly helpful. The dragon said you were the once and future king when I first met him, and then the Druid boy, he's the one who called me Emrys."
"The Druid boy who didn't talk?" Arthur said, skeptically.
"He did talk," Merlin protested, seeming to forget for the moment that he was tied up and at risk of execution. "In my head. That's how I met him. He called to me."
"Like the dragon called to you?"
"Yes," Merlin said, eager now that he thought Arthur understood. Arthur did not. "I haven't learned how to do that on my own yet. I think it might be a Druid thing."
"A Druid thing."
"A dragon and Druid thing?" Merlin shook his head. "Anyway, that's not the point. The point is, we have a destiny together. To bring back magic and unite Albion. To bring about a new golden age." He looked so painfully hopeful as he said it, as if he was practically begging Arthur to believe him.
"Merlin," Arthur sighed. A picture was starting to form in his head, and as relieved as he was about it, it wasn't pretty. "Here's what I think happened. Whatever magic you already had in you when you came to Camelot, it made you vulnerable. You've admitted that the dragon and Gaius have been lying to you, manipulating you. I don't know what my father has to do with any of this, but he wouldn't harbor a sorcerer, and he certainly wouldn't give you to me to protect me."
"But I have protected you!" Merlin protested. "I've saved your life so many times I've lost count!"
"All right," Arthur said, holding up a hand. "Leaving that aside. Has anyone besides this Druid boy ever said you were the Emrys? Has anyone other than the dragon said I was this once and future king?"
"Well, no, but--"
Arthur silenced him again. "So you have no confirmation about any of this. No evidence."
Merlin stared at him. "But it was on the wall."
"Let's say, for the sake of argument, that there is a prophecy. What proof do you have that the dragon and Gaius haven't simply been using it to manipulate you? What if it was never about us in the first place?"
Merlin stared at him as if he'd never even considered the idea, which wasn't surprising. Merlin was far too trusting. No wonder it had been so easy for the dragon and Gaius to fool him into this subterfuge. To take advantage of him and try to use him to undermine the laws against magic. Obviously his father would never change the law, but they clearly thought change was possible during Arthur's reign. He almost admired their cunning, because he had effectively done the same thing himself in using Merlin to undermine the First Code. But unlike them, he wasn't willing to destroy Merlin for his own ends. Merlin had insisted on being trained, and Arthur had eventually recognized Merlin's determination for the asset that it was. Whatever asset Gaius had made of Merlin's magic, it was not worth the cost of his soul.
"It has to be," Merlin said, with such blind faith. "It's what my magic is for. It's what I'm for."
"That's not what you told me," Arthur reminded him. "Before I knighted you, you said you were nothing. It was the magic that made you feel that way. That's the emptiness you felt. But as my knight, you proved the magic wrong."
Merlin was already shaking his head. "No, I said that because I was denying my magic. I didn't want to have it, because I had to lie to you about it. My magic is all I have."
There was a pitiful look in his eyes as he said it, and Arthur had seen it before. That was the pain that Merlin had been trying in vain to hide from him, over and over. The pain of his magic. He had probably been suffering this way for a long time. It was up to Arthur to show him that he was worth fighting for, no matter what the magic made him believe.
"Merlin, you have so much more than that," Arthur said, earnestly. "Look at everything we accomplished together in Gedref."
"But I did that with my magic," Merlin protested.
Arthur plowed on, sensing that he'd found the crux of it. "You said you were denying your magic. Did you use it when I trained you?"
Merlin shook his head. "I couldn't let you find out. So I stopped."
The news that Merlin had already proved able to resist his magic was a tremendous relief. Arthur knew that Merlin was something special, but this truly was the mark of it, that he could use that determination to fight against his corruption. That combined with his natural innocence had proved a powerful defense. "But you started again?"
"After Geraint died," Merlin said, sadly. "I had to use it. If I was just a knight, I couldn't give you what you needed. I couldn't protect you."
"Tell me everything you used it for in Gedref."
Merlin furrowed his brow in thought. "I tried to open the siege gate, and then when the patrol found me, I fought them with magic. Then I was captured, but I used magic to knock out the men who brought me inside. After that... I made the chandelier fall so I could earn Idriys' trust, so I could get to his papers for you. And then I unlocked a bunch of things and tripped some guards so I could escape with the papers and Palaemon's globe. That was it for a while, until I went in with the knights. I cooled the boiling water so it wouldn't hurt us, and then I unlocked the doors and cells to free the prisoners, and then I opened the gates!" He finished the list with a proud smile. "Arthur, I know all the magic you've ever seen has been used against you, but that's just because of the Purge. But I've been using my magic to protect you from the beginning, not just in Gedref. My magic is meant for you. It's my destiny."
"Meant for me?" Arthur asked, not sure if he was more worried or impressed by Merlin's long list. He had known some of it, of course, because Merlin had told it to him, excluding the magical parts. But he wondered if he would have been able to free Gedref before the harvest if Merlin had not done what he did. He had known that Merlin had practically handed him much of his victory by destroying Palaemon's enchantments, but this put it all into a new and uncomfortable light.
Magic could not be defeated without magic, Merlin had said. Arthur had known for months that Merlin and Gaius had been destroying magic, but he had not known that they had been using Merlin's magic to do it. Could his father truly not know all this? It was hard to believe. Perhaps there was some arrangement after all. One between his father and Gaius, to harness young, powerful sorcerers and use them to defend the kingdom in secret. Arthur had wondered about Lord Wichard's physician when he heard that he had been an apprentice to Gaius, just as Merlin had been.
The physician had seemed fine, but then so had Merlin, until tonight. Perhaps Gaius did know of a way to preserve his apprentices from corruption, and Merlin was being protected by it. It would be easy for the old man to slip it into one of his potions. It might even be in the relaxant, as Merlin had been taking it regularly during training, and then again since he had returned from his adventure in the castle. But then why not use it to help others? Why not give it to people like Linette, who had acted with good intentions? Surely if it could protect someone with as much magic in him as Merlin, a petty sorcerer like Linette could have been helped rather than executed. But his father was rarely rational when it came to magic. At times he would prefer to burn down an entire village if it destroyed even a single enchantment. That was not how Arthur intended to rule, when his time came. Camelot's worth was in its people, and saving them was better done through other methods than punishment.
"Yes," Merlin said, earnestly. "Because you're my King. That means you're meant to have it, so we can unite Albion."
Arthur frowned. They were back to that prophecy again. It was evident that Merlin had based much of his self-worth on the idea that he was this Emrys, despite admitting that he didn't even know what the name signified. But Merlin had been equally dedicated to being his knight. It was clear that what Merlin truly needed was a sense of purpose, of belonging. Merlin needed to serve him, in one way or another, out of love or some deeper urge. Arthur simply had to make him see that there were healthy ways of service, and there were unhealthy ways. It was no wonder that Merlin had been so obsessed with dying when he believed that he needed that corruption inside of him in order to be useful.
"Merlin, as grateful as I am for all that you've done on my behalf, I need you to stop. You have to deny your magic again, as you did for me during your training."
"I can't," Merlin protested. "What if Camelot's in danger? I have to use my magic more, I have to get better, stronger. I have to be as ready to use it as I am a sword."
"Is it?" Arthur asked, concerned. They had only just dealt with one threat. Could there be another coming so soon?
"I'm not sure," Merlin said, glancing away. He always did that when he knew something he didn't want to tell. Arthur had always considered it to be part of Merlin's odd charm, but some of that charm had worn off now that he knew the kinds of secrets that glance might be hiding.
"Does Gaius know something?" Arthur pressed.
"It's nothing to do with Gaius," Merlin said, and that was the truth at least. "I want to tell you, Arthur, I swear. But I can't until... until I get permission. It's not my secret to tell." He gave Arthur a painfully earnest look.
Arthur gave him a disapproving one back. "How many other secrets are you keeping that aren't yours?"
Merlin glanced away.
"All right," Arthur said, pinching the bridge of his nose. "I won't try to force them out of you, as long as you can honestly tell me that whoever it is means Camelot no harm, and that you will seek permission as soon as possible and then tell them to me immediately."
"I will," Merlin said, and he had that determined look about him that meant that Arthur would likely soon be served a whole feast of secrets. He wasn't sure if he was glad about that.
Merlin shifted against the tight bonds of the ropes. "Will you untie me now?" he asked, hopeful. "I'm sorry I scared you before. I sort of panicked."
"No," Arthur said, stern despite his regret.
Merlin looked puzzled. "What do you mean, no?"
"Merlin, I realize you sometimes have trouble with subtle details, but I have arrested you. Because what you have done is a crime."
Merlin stared, uncomprehending.
"If you refuse to stop using your magic and I let you go, I will be responsible for any further crimes you commit," Arthur explained. "Crimes which are classed as treason. The punishment of which is execution."
"Your father isn't going to execute you for treason," Merlin said, actually amused by this.
"It's not my father that I'm worried about!" Arthur said, growing frustrated. "It's you! And I am the Crown Prince. After everything you've learned, do you still have no idea what that means? What kind of damage it would do if I was seen to be publicly defying my father?"
"But we just did that," Merlin said. "With the First Code. And it was fine."
Arthur rubbed at his temple, feeling a headache coming on. "What we did was a tremendous risk, and it only worked because of my careful planning and your newfound ability to actually follow my orders."
"And my magic," Merlin insisted.
"Yes," Arthur admitted, his teeth gritted. "And I am extremely unhappy about that fact, because the entire point of the exercise was to use a common man, and it turns out that my carefully chosen common man is a sorcerer."
"Yes, oh," Arthur said, trying his best not to lose his temper. He had done enough damage to Merlin for one night. "If you are caught, not only will you be executed, not only will it cause a massive crisis of leadership, but everything we did in Gedref will be undone. So yes, Merlin, I need you to stop using your magic, right now, and I need you to promise me that you will never use it again."
Merlin was crestfallen. "But I tried that and it didn't work. Arthur, I don't just have magic, I am magic."
"And who told you that, then?"
Merlin bit his lip. "They weren't lying about everything. And if I can't use my magic, I can't protect you. I can't do anything."
"You can be my knight," Arthur insisted. "I know much of what you did in Gedref required magic, but not everything. I saw you fight as a knight, and nothing in that list you rattled off had anything to do with that. There are plenty of ways to open doors that don't require the corruption of your soul. I need you alive so you can be with me, so you can be my advisor, my grain of sand. I need you to stop using your magic so I don't have to watch you die." The last came out with a waver of emotion, despite Arthur's best attempts to stay calm.
But it was the last that finally seemed to get through to Merlin. "You'd let me burn?" he asked, quietly.
"If my father found out, I would have no choice," Arthur admitted, hating the truth of it.
"Is it because I have magic?" Merlin asked, his own voice wavering now. "Because you can't love a sorcerer?"
"I love you, Merlin," Arthur said, though the admission was hard to make, now that he knew. "But you cannot have magic. I need you to accept that. I'm going to do everything I can to find a way to get it out of you, but if you refuse to cooperate, if your loyalty lies with magic and not me, then I'll have no choice."
Arthur returned the sword to rest against Merlin's neck, and watched as Merlin struggled with his ultimatum. After a wait, he seemed no closer to a decision, and Arthur sighed.
"Do I have to decide now?" Merlin asked, looking devastated. "What if it's not possible? What if I really am magic? What if taking it away will kill me? What about Camelot?"
"Camelot will be fine," Arthur assured him. "Perhaps some threats might not be solved as easily as they would be with your help, but they will be solved. As for the rest, that will require investigation. Until I can find something that will remove your magic, you can take the time to make your decision."
"Between my magic and my life," Merlin said, bitterly.
"Between a future at my side and the destruction of Camelot," Arthur corrected. "But as I won't see Camelot destroyed, then yes. You pledged your life to me, Merlin. I promise you that I won't let you burn. But I can only keep that promise if we make the decision together, and soon."
Arthur knew that the choice was a cruel one, far crueler than it had been to ask Merlin to give up his victories and his armor. But Merlin would understand once he was free of the influence of the corruption. Once he saw that he would still have a place and a purpose without his magic. Arthur hoped he would make the right choice, because the grief inside him still threatened to swallow him up, and if he had to execute Merlin, he wasn't certain he would survive the task himself. Perhaps his father had been right about that, too. To love was to court destruction, and to lose Merlin now, to be responsible for his death, would surely break him, as it nearly had in Gedref.
"Do I have to stay tied up until then?" Merlin asked, and Arthur could see him trying to be brave, pushing back his fear.
"If you swear to me that you will not use any magic, that you'll do as I say and trust me as you have before, I'll untie you. I know that you have the power to free yourself, and I appreciate the fact that you haven't. If you had acted against me at any point tonight, it would have... forced the issue."
Merlin took this knowledge in. "I swear," he said at last, quiet but genuine.
Arthur could not suppress his shudder of relief. There was a chance, a real chance, that Merlin could be saved. It wasn't too late, not yet. There would be no time to waste, because it was clear that the magic had a deep hold on Merlin despite his obedience. It would be a war for Merlin's soul, between Arthur's will and the strength of the corruption. But Arthur had not lost a war yet.
He put his sword aside and untied Merlin slowly, still cautious in case Merlin's cooperation was a ruse after all. But Merlin's eyes remained blue, and he was pliant and subdued. Merlin loved him and would obey his King. In return, Arthur would take care of him, and ensure that if he suffered, it would be for a greater purpose.
Arthur rubbed at the rope marks on Merlin's wrists and ankles as he freed them, and brushed a gentle hand through Merlin's riled hair. He could see that Merlin was trying hard not to cry, and Merlin did not reach out for him as normally would. Arthur regretted that he had hurt Merlin tonight, that he might have to hurt Merlin again, but as with Merlin's suffering as his knight, he would not regret the purpose of that pain.
He saw Merlin looking towards the door, and knew this last thing would be the hardest.
"Merlin, until I know I can stop your magic, I have to keep you here," Arthur told him.
"I'm your prisoner," Merlin said, realization dulling his voice.
"For now," Arthur said, trying to soften the blow. "I'm going to do everything I can to find something we can try, maybe even as soon as tomorrow. My father has vaults full of enchanted objects. I believe there might be something there that can help us. Try and think of it as a day off." He mustered a smile, and Merlin tried to smile back, but his chin was already quivering.
"Do you need anything before you go to bed?" Arthur asked, the need to escape becoming overwhelming. He collected up the ropes and his sword. "I'll bring in breakfast tomorrow."
Merlin shook his head. Arthur could tell that if Merlin spoke, he would fall apart, and felt the same. His heart was tight with pain that the one thing he couldn't bear to do was hold Merlin close. It was what they both needed, but neither of them could stand it. Not tonight.
Tomorrow. Arthur would fix everything tomorrow, and then he would be able to let Merlin out again. Everything could go back to normal. There had to be something in those vaults, even if its contents were largely uncataloged and covered in dust and cobwebs.
Magic could not be defeated without magic. If it was true, then that was what Arthur would do. He would use the enchantments of the Old Religion against the magic that was within Merlin. He would defeat magic with magic. Whatever it took.
He left Merlin's room and closed the door behind him, retrieved his keys and locked it. He rested his forehead against the wood and listened to Merlin's quiet, tight sobbing, his own grief slicing into his heart like shards of steel.