The Doctor turned to face Arthur and Merlin, still hidden behind the curtain. "Run," he said calmly. Arthur darted for Merlin, pulling him along to the door at the far end of the room. The Flinx had a small gun hidden in his costume, one that he pulled on the trio, firing as they ran. Past the door, Merlin uttered a few words and his eyes glowed. The door slammed shut and locked. The Doctor led them down the corridor with haste.
"What now?" Arthur demanded as they rounded a corner.
The Doctor thought quickly as they moved. "We need to get Opic out of the game. He's the puppet master. Without him, his play falls apart."
The prince's hand instinctively fell to the hilt of his sword.
"No! Nonono," the Doctor frowned, shaking his head violently. "No killing!"
"Why not? They've killed-"
"That's the point," the Doctor interrupted. He stopped running and placed a hand on the blonde's arm. "If we kill them, we're no better than they are. We have to be superior beings and find a way to resolve things peaceably."
Arthur scoffed at that. He'd seen many a conflict resolved through good battles. But if that was how he wanted to go about saving the world...He was the expert, after all.
"So what's our plan?" Merlin asked, glancing back at the way they had come. The hall was empty.
"We need to lock them up. I know a good prison, protected by the Shadow Proclamation. That should-"
The Doctor's plans we interrupted as a form blindsided Arthur. He went down, tangled in red cloak. Chain mail clashed together as the two men rolled. Arthur's head came up. The man underneath him rolled, flipping the prince under his body, and-
Arthur's head came up.
"It's the Flinx!" Merlin gasped, turning to the Doctor. He was busy pointing his sonic screwdriver at a floating metal object. "What is that?"
"An assassin drone. I've disabled it," he replied as it clattered to the stone floor. They turned to help the prince, but came face to face with two identically dressed Arthur's doing battle.
"Doctor...what do we do now?"
"Assassin drones, Warlocks, and doppelgangers.. oh my!" The Doctor grinned to himself.
The two princes fought, swords slashing about the air, echoing through the hallway.
"Doctor..." Merlin started. "How do we tell who's the real one?"
"Weren't you watching?"
"I looked away to see you! That bloody assassin drone?"
The Doctor paused, "He was expecting this. Planned it. Oh, that's very clever indeed."
"Doctor!"
"Right. Right. Well, you're the one that's a warlock. Any magic?"
"Because I just happen to own a wizard guide book that tells you how to find your prince boyfriend when he and his alien twin are in the middle of a fight to the death!"
"Alright, calm down. We'll just need another way of telling..."
The princes were tiring, drawing back more often to catch breaths. Merlin watched intensely. He'd seen the prince train nearly everyday for years. "Why am I having trouble seeing which one had Arthur's fighting pattern?"
A few more of Opic's drones rounded the hallway corner. "Look out!" The Doctor pointed his screwdriver at a drone, which immediately fell to the floor. Merlin took out the other.
"You can't see a pattern because they both have it." The Doctor answered.
"What?"
More drones rushed in, the clusters growing stronger in number with each arrival.
"Keep in mind we've no idea just how long this Flinx has been here. He's literally become Arthur. There's no difference."
Merlin slashed his drone down before turning to look at the princes. "There is a difference."
"What?"
Merlin gripped the Doctor's arm, "As soon as you know who the fake is, you kill him. Understand?"
"Merlin-"
Merlin pushed the Doctor, who fell onto his back as a new wave of drones appeared. Merlin didn't fight them off, just raised his arms out. Ready to be killed. The Doctor screamed upon understanding, "Merlin, NOOO!"
A drone shot him, and Merlin fell.
The world seemed to slow for Arthur. He watched Merlin die. Again. "Merlin!" He cried.
Consumed with rage, he slashed at the Flinx, sword slicing through it's arm. The Flinx drew back, and Arthur ran to his beloved. Only partially noticing the Doctor, who covered them with his screwdriver as he turned to chase the Flinx. The world was slow... agonizingly slow. Sparks flew around them, a few drones combusting. Arthur cried as he lifted Merlin into his lap, burying his face in the boy's hair. "You cannot die on me again! I won't let you! Wake up Merlin! Wake up this instant!" he begged.
But... Merlin didn't wake up.