Arthur thought that it would be relatively simple to determine the cause. After all, when Merlin was still alive, Gaius always had an answer and a cure quickly enough, often with hand-waving and some rubbish explanation that Arthur overlooked because Merlin was already dragging him off to fix whatever it was plaguing Camelot. And by the time things had settled down enough for Arthur to think about what had just happened and wonder, there was another crisis.

Now with Merlin gone and days without an answer, Arthur was growing impatient. It wasn't as if Gaius wasn't trying, though. The books by Gaius's bench grew, potions and strange crystals and unidentified herbs piling up, and more often than not, Gaius bustled about his laboratory, muttering to himself.

The voice, too, changed as time went on. Merlin, because Arthur was certain it was his voice plaguing him, was growing louder, his words clearer, and it wasn't just insults but observations, suggestions, as if he were still Arthur's unacknowledged advisor and not some ghost haunting him. A melancholy voice, wistful at times, then growing cheeky again as if to try and fool Arthur into thinking there was nothing wrong.

But everything was wrong and finally Arthur had had enough.

Standing over Gaius who was giving him a put-upon look, Arthur crossed his arms and stared back at him. "You must have found something by now, Gaius." There was a flash of guilt in Gaius's eyes and Arthur's anxiety peaked. "Out with it. No matter the cost."

There was hesitation and a kind of dread in Gaius's voice, but the old man seemed to gather himself together and said, "Sire, I… Uther accused Merlin of sorcery."

Arthur remembered it well. He'd pleaded with his father, begged him but to no avail. The fact that Merlin looked terrified hadn't helped, but then he always looked like a scared rabbit around Uther. Arthur brushed the very idea aside, shaking his head. "Yes, it was ridiculous, of course. He was no more a sorcerer than I am."

Guilt deepened in those old eyes and then Gaius looked away, down at his hands. "Sire…."

Merlin's voice was clear as crystal, sounding almost breathless with apprehension. Don't listen to him. He's just trying… Arthur, I think you are needed downstairs. The patrol has news of those bandits….

The patrol wasn't due to be back for days. Arthur's suspicions began to grow, and he needed answers. Brushing aside the increasingly worried voice, Arthur said, "Out with it, Gaius. The truth this time."

Please, I didn't want you to find out this way. I didn't mean to….

Arthur sent a scowl back toward where he thought a ghostly Merlin might be hovering, then turned to Gaius, frowning down at him, and waited for him to either reassure Arthur or break his heart.

It didn't take long. Gaius said, "Uther was not wrong in his suspicions."

For a moment, it didn't make sense; it was mere noise. Even if he'd been prepared, with horror and outrage growing in the back of his mind, it hadn't been nearly enough time or preparation, not when he'd given Merlin all of his trust.

And then it hit him. Merlin had been playing him for a fool all these years after all.

There was a babble of excuses behind Arthur, mixed in with denial and apologies, but he ignored it. He'd be damned if he'd listen to that lying idiot just then. Instead he focused on what Gaius was telling him. It was easier than letting the anger overwhelm him.

"You are not under a curse nor a spell but there is magic there." At that, Arthur nodded. It was a relief, small amongst the fury bubbling away in his chest, but still it would mean that he wasn't under someone else's control.

Gaius gave a little sigh, frowning up at Arthur as if able to read how truly upset Arthur was, and then said, "Merlin isn't quite dead, nor is he alive. He seems to be caught between worlds. As far as I can ascertain, when he tried to escape the flames, he thrust himself into the magical realm but not fully. Something held him back, and it was enough to keep him from reappearing elsewhere. Strong emotion or a connection so deep that he could not bear to lose it. And now he's trapped."

If Arthur had been a little less furious, he might have tried to understand what Gaius was implying. After all, before this debacle, Arthur would have said that Merlin and he had an unbreakable bond, guarding each other's backs with all the strength they could muster, willing to die for one another over and over again.

And now, Arthur didn't know what to think. He wanted to strangle Merlin; he wanted to shake him until all the secrets he'd held spilled out and Arthur could finally find honesty between them. He wanted to beg Merlin's forgiveness for not being more understanding. But mostly he wanted to throw things. At Merlin.

In a flat, hard voice, Arthur said, "He's alive then?" When Gaius nodded, Arthur was back to furious. "Good, because when he gets back, I'm going to kill him."

There was a whimper in the air, Merlin's voice heavy with grief, but Arthur ignored him, tried to ignore Gaius, too, when Gaius said, "Sire…."

That just set Arthur off again. "He couldn't tell me himself? He's been lying to me all this time?"

"Would you have spared him if he had?" Gaius seemed almost defiant.

Arthur couldn't bear it any longer. He grabbed something on the bench, didn't bother to see what it was, something oddly-shaped and probably precious to Gaius, but he didn't care. Throwing it against the wall felt good, the first he'd felt in quite some time. The clay flagon shattered into a thousand pieces, the liquid within staining the stone green and then orange as it ran down the walls.

When Gaius moved to protest, Arthur shouted back at him. "I trusted him. I'll throw him into the stocks until the wood rots away. I'll make him clean my boots with his tongue and thank me for it. And everyone else's, too. And clean the stables with a spoon. And the cesspit. And the swamp beyond that." When Gaius just gaped up at him, Arthur spun around, his hands fisted and threatening, and yelled into the air, "Do you hear me, Merlin? I'll make your life a living hell when I get my hands on you. You think things were bad before. Just wait."

From behind him, softly as if trying to calm Arthur down, Gaius said, "Sire, this is not helping."

Arthur wheeled, shouting, "He lied to me, Gaius. Was there even one moment of truth in all that time?"

"More than you know." Gaius rose up, his arms crossed, his posture both defiant and deferential. Staring at Arthur a moment, he said, "He hated it, every single day hiding himself from you, but with the king so adamant about sorcery, what else could he do?"

Loathe to admit that Gaius was right, that Merlin would have had to hide every moment in Camelot, still Arthur said, "He could have trusted me."

I did trust you. I do, Arthur.

While Merlin was whispering in his ear, Gaius was giving him a look, one filled with disbelief. "And what would you have done? Helped Uther build the pyre? Thrust the torch into it yourself?"

Arthur was appalled all over again. "Gaius, never. How can you say that?"

He'd been unable to save Merlin before, and that Merlin might have thought Arthur capable of allowing it, of wanting it, was horrifying.

Merlin was silent, though, as if he did think Arthur might have condemned him, and that was even more heart-breaking than Gaius's accusations.

Standing there a moment, looking down at his feet and then back up at Arthur, Gaius lifted his head in defiance. He said slowly, carefully, pointedly, "It was I who cautioned Merlin to remain silent. Arthur, you must realise that your father has murdered countless innocents in his quest to destroy magic. I had friends and family who died in agony, those I loved. I thought Merlin had died, too, and I had done nothing to save him."

Grief caught in his throat, it took Arthur a moment to breathe again. "Gaius, I don't… I know it's hard with my father. I know that he's done terrible things and I haven't been able to stop him. I've even helped him at times to my great shame. But I don't know what to do to fix this."

Gaius slumped a little, gave a deep sigh. "It is hard to know who to trust in these trying times. Forgive me for thinking the worst."

Arthur, can you… can you ever forgive me, too? Even if you are still a prat.

He wanted to forgive them both, but it was still impossible to think his way through it all. Instead, pushing all the anger and hurt aside, he said, "So Gaius, how do we bring Merlin back?"