If you haven't read Ultra-Geek's Exaggerations and Overreactions, do so, not because you need to to understand this story, but because it will make your life better.
Disclaimer- I do not own Merlin. I would share him with you if I did.
The knights were unusually quite as they road into the courtyard. Arthur's grin wavered on his face as he went out to greet them.
"Back already? I thought it would take more time to finish sweeping the outlying villages. Was there trouble?"
Arthur looked from face to face. Grief was written on every feature. His knights stood before him looking broken, refusing to meet his eyes. All except Gwaine. He seemed to be removing a bundle from the back of one of the horses. A long, limp bundle…
Arthur's senses were dulled. He was so confused. "What's going on here?" He did a quick head count. "Where's Merlin?" Merlin would know what was going on. Merlin would tell him why everyone was so sad and quiet, and Merlin would help him fix whatever was wrong.
"Arthur," Lancelot's tearful eyes finally met his own, "I- I'm sorry."
"NO!" The shout startled Arthur; he hadn't noticed Gwen come to stand beside him. As Gwaine walked past them, she fell to her knees sobbing, "No, no, no…" Arthur didn't understand. What had she seen that had upset her so much? Arthur really needed to find Merlin. Merlin would explain what was going on, and he could make Gwen feel better. He was good at that.
Gwaine would know where Merlin was. Arthur followed him as quickly as he could. The knight was already out of sight, but Arthur was sure he was headed to Merlin's chambers. Maybe Merlin was already there; maybe he'd gone around a back way. Arthur would find Merlin, Merlin would explain what had happened, and they would fix it, side by side.
When Arthur entered Merlin's room, Gwaine had already laid his bundle down on the bed, and was in the process of unwrapping it. This was very odd. Arthur's confusion soared to new heights. What in the world would Gwaine be bringing to Merlin's room? Why would he put it on the bed? And where on earth was…
The wrappings fell away to reveal a shock of dark hair, a pale face, and a worn red neckerchief below.
Oh.
So… this was one of Merlin's jokes. It must be. Arthur was rather impressed with how still he was being, but it wouldn't last. Any second, Merlin would pop up and start blathering away. He would probably be upset with Arthur for not overreacting and behaving foolishly in front of everyone, as was doubtless Merlin's intent. Soon, blue eyes would pop open, and Merlin would be complaining and joking and calling Arthur a prat. Any moment now…
But as Gwaine sat with his head bowed, and Arthur moved closer to the bed, Merlin didn't laugh, didn't stir, didn't breathe, and Arthur's blood turned to ice.
Because he could only lie to himself for so long.
As he knelt by Merlin's still form, he finally admitted what he had realized when he had entered the courtyard, seen the sorrowful faces, the empty horse, Lancelot's tears, Gwen's anguish, and that horrible, limp bundle in Gwaine's arms.
Merlin was dead.
His servant—friend, warlock, advisor, brother— was dead. Arthur would never hear his laugh, or see his eyes— now bright piercing blue, now sparking, powerful gold— again. Never again would he see his friend trip over a stack of armor, or the stairs, or his own feet. He would never feel the warmth of loyalty so fierce and powerful that it could, quite literally, move mountains. No one to call him "prat." No one to watch his back in battles. No one to look out for.
His idiot was gone.
The numbness he had been experiencing departed as cold horror settled over him. His strength left him as he reached out to touch Merlin's hand. He shuddered. It was boney, cold. Corpse-like. He chaffed it uselessly, trying to do something, anything for the faithful friend who he could no longer help or protect. Feeling cold tears in his eyes, he carded his hand through Merlin's hair.
Blood. There was dried blood in Merlin's hair. He gently turned his dead friend's head to the side. His stomach revolted as he found not a lump, but a dent in the back of Merlin's skull. He stood quickly, looking down at Merlin as he processed the cruelty and the cowardice of his friend's killer. Rage, hot and restless, filled his body. Every muscle tensed.
He met Gwaine's haunted, dead eyes. In a voice shaking with anger, Arthur ground out the only question that mattered.
"Who?"
Gwaine told him the tale of the ambush. He was emotionless, empty, as if his soul had died with Merlin. Gwaine had seen everything and hadn't been able to prevent it. He had seen that the assassins were clearly targeting Merlin, drawing him away and distracting him. He had seen the leader of the group sneak up on Merlin and bludgeon him from behind. He had seen his friend fall as the assassins retreated. He had been the first one to reach Merlin. He had seen Merlin's eyes slip closed.
Merlin hadn't opened his eyes again. Gwaine had held him as they desperately road for Camelot, trying to get Merlin help. Merlin had started seizing halfway there. Soon, it had gotten so bad that Gwaine couldn't safely ride with him anymore. They had continued on foot, Lancelot and Gwaine carrying Merlin between them. Then, Merlin had started gasping for breath. They had been forced to stop and prop him up. The knights had done all they could for him, but eventually, Merlin slipped away.
As Gwaine finished his story, Arthur's fists clenched. "So what you're saying is, you know who did this, and he's still out there." Gwaine nodded silently. "Good," Arthur said, nodding, "That's good."
Gwaine's head jerked up, and he squinted at Arthur, not understanding. Then it clicked. A frightful, wolfish grin that had nothing to do with happiness spread across his face.
"Tell the others, and prepare to leave." Arthur turned his attention back to his the body in front of him, not bothering to see if his order would be carried out. He knew it would be. He knelt beside Merlin once more. He gripped his friend's shoulder. This at least was as it has always been—solid, real, and always at his side. But this time he wouldn't be.
"I'll be back soon."
Arthur stood beside the fresh grave. He was shaking. There was still blood on his hands, the stink of smoke in his nostrils, and the aura of death surrounding him.
"He's dead, Merlin." Arthur swallowed. "He's dead, and he suffered. He suffered as much as I could make him. " Arthur recoiled at his own satisfaction. It had felt good to destroy the man that had shattered his world, that had killed the best man he knew, his brother, his friend. "They're all dead, but it doesn't make any difference, does it?" Arthur's voice broke; he had battled his sorrow with rage, but the sorrow was stronger, and it was winning.
"You're still gone, my knights are still broken, and Gwen… she can't even look at me after what I've done. I'm supposed to be this just, merciful king, but he- he killed you, and he deserved worse than he got, but now… my people know, they KNOW, and they don't believe in me anymore. Camelot is falling, Albion is falling and—" Arthur broke into a slightly hysterical laugh as the tears pushed forward, "And I don't care!" Arthur fell to his knees. He breathed deeply, trying to regain some composure.
"You said once that we were two sides of the same coin. It's not just that I don't want to do this without you. I can't do it. I'm sorry." He drew his dagger. He positioned it over his heart, feeling at peace for the first time since Merlin's death.
"It's all over."
Arthur awoke with a start. He was on his feet and heading to Gaius' chambers before he knew what he was doing. He barged in, and saw Merlin lying there, pale and still in the moonlight, and his heart nearly stopped, but no, Merlin's chest was moving. He was alive. He was just on the mend from his "overreaction." But Arthur had to be sure. So, naturally, he grabbed Merlin's shoulder (trying not to think of what it felt like when he'd done the same thing in his dream), and shook him vigorously. The reaction was immediate. Merlin popped up, flailing, panicking, and gasping something about giving the wyverns back their cake. His eyes finally focused on a madly grinning Arthur.
"A'th'r was'sit? S'dark… why're you… what's… ugh… why?"
Arthur ignored his friend's incoherent babbling. "How about this," Arthur said, "You don't die, and I won't become a horrible, vengeful, desperate king who destroys Camelot."
Merlin gaped helplessly as his tired brain tired to process what he had just heard.
"Deal?" Arthur prompted.
"Wha…"
"DEAL?" Arthur was now looking quite manic and dangerous.
Merlin nodded slowly. "M'kay," he managed, weakly.
"Great," Arthur heaved a huge sigh of relief, clapped Merlin on the shoulder, and walked briskly out of the room.
Merlin stared after his friend for a few minutes, eyebrows still drawn together and mouth hanging open. As he lay back down, he sincerely hoped he that wouldn't remember any of that thoroughly confounding conversation in the morning.
"Prat," he mumbled as he drifted off to sleep.