Arthur and Gwen had agreed that Gaius' chambers were the best source for a good poison. So, they'd made the short trek to the old physicians room, and now stood in front of the daunting shelf of various mixtures and concoctions.

"So…" Arthur began, "which one of these is a poison?"

"How am I supposed to know?" exclaimed Gwen, "I've never assisted Gaius in poisoning something before!"

"At least one of these has to be one, don't you think? I mean, that seems logical to me. A physician should have remedies and poisons for various things, right?"

Gwen sighed. "I don't know, Arthur."

She stared up at Gaius' immense inventory of potions. If only the physician was here to help them. He would know right away. But Gaius was nowhere to be found, apparently. Most likely he had been summoned to the King's chambers, and they didn't dare interrupt the King.

"Maybe we should test one of them," suggested Gwen. "Choose one that looks poisonous."

After a moment of thinking, Arthur chose a small corked vial with a metallic purple liquid. "This one looks deadly," he remarked with confidence. Then he furrowed his brow. "Wait a minute, who are we going to test this on?"

Gwen bit her lip in thought, a quirk that Arthur found rather cute. She looked pretty when she was baffled. He was snapped out of his daydream by a sharp comment from the maid.

"Arthur, stop staring at me and go get that rat!"

"Rat?" he asked, confused.

Gwen sighed and pointed. "The rat over there in that cage. There are three of them. Gaius probably uses them to test out remedies he makes. We could test the poison on them."

"O-oh," stammered Arthur, "right, of course. Exactly what I was thinking."

Though she tried to hide it, the Prince caught the slight eye-roll Gwen did. He went over to the cage and lifted up the lid. Hesitantly he picked up a plump rat by its middle, which caused it to squeak and squirm around in the process.

"Oh, dear Lord," he mumbled with a disgusted grimace. "These rodents are vile. I swear, if it bites me…"

"Just bring it over here and try to keep it still," Gwen ordered, and Arthur obliged.

"I'm surprised that you keep ordering me around like this," commented Arthur as he held the rat down. "You're really worried about Merlin, aren't you?"

Gwen poured a spoonful of the purple liquid. "Well, yes, but…"

Arthur raised an eyebrow. "But?"

"Of course I don't want you to die, either!" the maid blurted. She blinked, and blushed.

Arthur couldn't help but smile a bit. "Well, I appreciate that."

Gwen nodded a little and eased the liquid into the rat's mouth with some effort. She and Arthur watched eagerly, waiting for the potion to take effect. After a moment, the rat squirmed and went still. Hesitantly, Arthur took his hands away. The rat didn't move.

"It's… dead," said Gwen. She smiled. "We found a poison on the first try!"

Unfortunately, the maid spoke too soon. The rat twitched, and soon began swelling, growing bigger and bigger in size. It was now four times the size as it was before. Its eyes opened and locked on Gwen. With a deformed squeak/growl, it launched itself at her, the maid shouting in alarm. Arthur jumped in front of her and the rat collided with him square in the chest. He grabbed it and wrapped his arm around its throat, and in a few moments it was dead for real.

Gwen stood wide-eyed, staring at the mutated creature. "A-arthur…" she said quietly. "You… you took a giant rat for me."

Arthur looked from the rat to her. "Of course I did. Why wouldn't I? That would be a harsh way to go, don't you think? Mauled by a mutated rat."

"Er, I suppose, yes. Uhm… Thank you." Gwen was a bit baffled by the situation.

Arthur smiled. In a prince-like fashion, he took her hand and bowed, lightly kissing her soft skin. "Of course, my Lady."

This caused Gwen to blush fiercely. "Er…"

Arthur straightened up. "Let's find that poison, shall we?"

Gwen agreed, and they tested a different draft. This one only succeeded in turning the rat a bright shade of pink.

"There's only one rat left," Gwen observed, biting her lip. "If we don't succeed with this one…" Her sentence trailed off.

Arthur stared at the shelf, perplexed. He moved a row of vials aside, searching. In the very back of the shelf was a tiny vial. He furrowed his brow curiously and grabbed it, holding it gingerly in his hands. The vial was so small; it felt as if handling it too roughly would crush it.

"What's that one?" inquired Gwen, moving closer to see.

"I… don't know," Arthur replied, staring at the vial.

There were odd letters carved into it, looking like the runes from the script Gaius had shown him and Merlin. The liquid itself was menacing enough; it was black as ink, but shone with an eerie shimmer when the light hit it right. Arthur looked at Gwen. "Shall we?" The maid nodded in response.

"Let's test it like we would be giving it to the witch," she suggested, taking a small piece of bread from the table and breaking off a bit.

Arthur dabbed a couple drops of the liquid onto the bread, and Gwen gave it to the last rat. It nibbled it eagerly, quickly consuming it. The duo waited. A minute passed. Then two. Then three. They were soon about to give up hope when suddenly, the rat gave a squeak of alarm. It started convulsing; twitching at first, then violently. They watched in shock as the rat writhed, and then suddenly went still.

"Is it…" Gwen started to ask.

Arthur waited a moment before reaching into the cage and picking up the rat. "It's dead," he confirmed.

He turned the small vial over in his hands. "This is it," he said. "There isn't much in here. We only have one chance at this."

Gwen nodded. "I'll take it with me to the kitchen and put it in the bread. Maybe a little in the water, too, if it doesn't dye it black. Just in case she eats either one first."

"Good idea," the Prince replied. "Be careful not to waste a drop," he added.

Gwen nodded again and turned to leave. She hesitated, and then turned back to Arthur. Quickly, she leaned up and gave him a peck on the cheek.

"Wish me luck," she said softly with a smile. And then she was gone.