Unfortunately, I do not own Merlin. I would like to thank the actors in the show, because I would feel a bit weird if I didn't, since they are the ones doing the acting, creating the characters and all.
The impact hit Merlin in the chest like a boxing glove. The world spun, and Merlin had to make an effort not to fall over. He was clumsy at the best of times, and this certainly wasn't helping his balance.
Arthur turned, glaring at Merlin. He started to snap, "Merlin, why the hell did you push m-"
Then his eyes widened, focusing on Merlin's chest. "Merlin, what happ-" Arthur's eyes darted around, instantly taking in what had happened. The enemy queen with her hand still outstretched. The archer, standing in the shadows, lowering his bow after his shot went amiss. And the archer's arrow, clearly meant for Arthur, now buried in Merlin's chest. Around the shaft, Merlin's shirt was dark with his blood.
Arthur caught Merlin as he began to crumple. He lowered him to the ground. All around them, as Arthur's knights absorbed what had happened, and the enemy realized their trick had gone wrong, a battle started to rage between the two sides.
Arthur tugged the arrow from his friend's chest as gently as he could. It had struck him right below the heart. Merlin was losing a lot of blood. Too much blood. Arthur felt sick. He didn't know why. He'd seen blood before, thousands of times. But this time was different. Because it was Merlin.
Merlin could hear a steady pounding sound in the back of his ears, like the beating of a drum. It was starting to drown out all other noises. Except for one.
He could hear Arthur, somewhere above him, saying, "Merlin, wake up, you have to stay awake." It wasn't the words that intrigued Merlin, it was the tone. Somewhere between desperation and. . . was that pleading?
Merlin forced his eyes open and took a shallow, shuddering breath. It took a surprising effort. Arthur's face swam into focus above him, his brow creased with worry. "Merlin, oh thank God." Merlin was marginally surprised to hear the fervent relief in Arthur's voice, but he was slightly pleased as well.
"We have to get you to Gaius," continued Arthur, starting to stand up. "I refuse to let you die."
Merlin almost rolled his eyes, but all of his effort was being focused on remaining conscious. "Arthur," he muttered scratchily, "Don't be ridiculous. We're hours away from Camelot. I don't think I've got more than. . . a few minutes."
"No," said Arthur fiercely, "No, Merlin, you are not going to die."
"You're a liar as well as a prat." breathed Merlin. "Listen," he said, as Arthur showed signs of protesting again, "Listen, when you get back to Camelot, do this one thing for me. Ask Gaius. . . ask Gaius to tell you about magic. Tell him I told you to ask."
"Merlin," said Arthur, confused, "What are you talk-
"And one more thing," said Merlin, almost tiredly. "When you get a new manservant. . . make sure it isn't George."
"I'd never hire that clotpole. He's even more of an idiot than you are."
Merlin managed a half-hearted smile, though it was only a shadow of his old grin. The little color still left in his cheeks was fading. "And Arthur? I know you always insist you're the one giving the orders, but I have one last one. . ."
Arthur searched his eyes. "What is it?" His voice broke on the word 'what'. This couldn't be happening, Merlin could not be lying in front of him, slipping away.
"You are not allowed-" He broke off in a fit of coughing that felt like it was breaking him in half, but he determinedly forced himself on. "You are not allowed to blame yourself for me dying. It was not-" Merlin's voice was starting to fade. "Not your fault. I made my choice, and I'd make it again in an instant." He was struggling to breathe, but he looked up at Arthur, his expression as heart-breakingly earnest as ever. His eyes were steady despite the irregularity of his pulse.
"Goodbye, old friend." murmured Arthur. Merlin smiled faintly, and his breath came out in a tiny huff. His eyes fluttered closed. The little tension still in his body left it, and Merlin slumped silently against Arthur, his head lolling limply to one side.
Arthur set the body of his oldest, truest friend down, but he remained kneeling by Merlin until the battle had ended, which wasn't long. Camelot's knights were more than a match for the ten or so servants Queen Alicia had been able to muster up.
Leon put a hand on Arthur's shoulder. Gwaine pulled him to his feet, his expression unusually serious. Arthur straightened his shoulders and took a deep breath. "We ride back to Camelot in the morning." Arthur was surprised at how shaken he sounded. Well, he was shaken, he thought indignantly, he had a right to sound it. Realizing that he was being defensive with himself, he shook his head and said, gruffly "May I have some time alone?"
The knights respectfully left him alone, probably to be alone themselves. Each and every one of them had been friends with Merlin as well. Leon, Elyan, Percival, and especially Gwaine and Lancelot. It would take time to process that Merlin was really. . . gone.