When Merlin did arrive back at Gaius' chambers, then man was sitting in a chair, his arms folded, looking understandably upset.
"Where have you been?" Gaius asked sternly.
"With Arthur." Merlin answered. It was bit vague, but it was the truth.
"With Arthur?" Gaius repeated, "All night?"
"Yes." Merlin replied, then deciding it was best to just come out with it, "There's been a bit of a…situation."
"What is that supposed to mean?" Gaius demanded.
Soon, Merlin had explained the sorted events of the previous 24 hours.
"Did you know that Arthur had a foster sister?" Merlin asked, once he was finished.
"Little is known about Arthur's time in the colony, even by those in the most inner circle." Gaius explained, "Although, when he was found there was young girl with him. I never saw her myself, but she was said to be deaf. She was released a few days later." After a beat he added, "But Arthur's right, we must get her out of here as soon as possible."
"But how?" Merlin asked, "Valliant's around her practically every second of the day."
"Not when he's in the arena." Gaius replied, "While he's fighting be ready to take her from the stands. I'll make an excuse to leave the city so that I can accompany you."
"Gaius." Merlin began, "I can't ask you to do that, it's too dangerous…"
"It's too dangerous for you to go alone." Gaius insisted, "I'm going with you and that's final."
Shortly after that, Merlin told Arthur what had happened.
"You told Gaius?!" Arthur exclaimed, pacing the floor, "What the Hell were you thinking?!"
"I was thinking he knew something was up, and that he could be trusted." Merlin argued.
"He could— "Arthur began, face palming, "Oh, your poor naïve boy no one can be trusted!"
"But he can." Merlin insisted, "Trust me."
"Did you hear what I just said?" Arthur asked.
"Well, if you didn't trust me, then why did you even tell me about her?" Merlin challenged.
"Because you found out and I needed help and I didn't know what else to do but to trust you!" Arthur admitted.
Merlin took a minute to gather his thoughts. "Look," He began, finally "Given all that you've been through, I understand why it's difficult to trust. And I get why you don't want to trust me, I mean, you've known me what, three days? But I promise you, if anything happens to your sister on my watch, you can take it out on me. I might even deserve it."
Arthur thought on this for a moment. "Alright." He agreed, "But I'm holding you to that."
At last the time came. As Valiant went into the stadium, facing off against Sir Ewan, Merlin came up to Arrietty, tapping her on the shoulder. "It's time." He informed her, making sure she saw.
Arrietty got up and went quietly. She knew she need to go if she wanted to be back by the time her parents returned. She was cutting it close as it was.
Valiant pinned Ewen with his shield. "Strike him." He ordered.
The serpents came out of the shield, but did not immediately attack.
"Strike him!" Valiant repeated the order.
The snakes bit Ewen, paralyzing him. Valiant hit the man then stood up, causing the cord to burst into applauds.
That was when someone noticed Sir Ewen lying motionless on the ground.
"I think he's badly hurt." A bystander told Gaius, just as Merlin and Arrietty got to him.
"I have to go see to him." Gaius said, grabbing his medical bag, "Go wait for me by the woods until I can come."
Merlin and Arrietty did as they were told, only to find themselves waiting in woods for hours. Merlin started to get worried. Stay here. He signed, using what they had taught him last night, then said, "I'll go see what's keeping Gaius."
When Merlin entered Gaius' chambers, he was tending to Ewen. "I told you to wait with Arrietty."
"I had to see what was keeping you." Merlin explained, "How bad is it?"
"It's most odd." Gaius admitted, "Look at this."
Merlin got closer, looking at the two tiny marks.
"See these two small marks?" Gaius continued, pointing them out, "Looks like a snake bite."
"How could he have been bitten by a snake?" Merlin asked, "He was injured in sword fight."
"But the symptoms are consistent with poisoning: slow pulse, fever, paralysis." Gaius countered.
"Can you heal him?" Merlin asked.
"Well, if it is a snake bite, I'll have to extract venom from the snake that bit him to make an antidote." Gaius explained.
"What happens if he doesn't get the antidote?" Merlin asked, thought he was afraid he could guess the answer.
"Then I'm afraid there is nothing I can do for him." Gaius sadly declared, "He's going to die."
"He was fighting Knight Valiant." Merlin thought loud, the wheels turning his mind. Perhaps there was more to Valliant's good luck charm then met the eye.
"What's that?" Gaius responded.
"Nothing." Merlin lied.
By that point Arrietty got tired of waiting for Merin by the woods and went to look for him. Managing to get back in the castle—she had serval qualms about their security—she found him, of all places back by Valliant's guests chambers.
"There you are. "She declared in what she had meant to be a whisper, but didn't get it quite right, "I know you think Valliant's a bad guy, but is this really the—" Merlin grabbed her and slapped a hand over her mouth.
"I need you be quiet." Merlin pleaded, "Just for a moment. Just until I figure something out, okay?"
Arrietty, not being able to hear what he said, kept struggling, until Merlin turned his head, then unable to help herself, turned her head to see what he was looking at.
Valiant sat down in front of his shield and putted a white mouse from a cage, dangling the poor struggling creature by the tale. "Dinner time." He called out, "Come on."
Suddenly a snake came out of the shield, eating the mouse.
Merlin quickly scurried away, holding Arrietty tightly by the wrist. However, Valiant heard them and followed. Merlin pulled them both into the nearby alcove, but Arrietty pulled away and stepped out, revealing herself to Valiant.
"Ah, there's my little friend." Valiant said, "I was starting to get worried."
"Sorry." Arrietty responded, trying a appear contrite and covered up her shock.
"Well, you did warn me you were curious and reckless." Valiant replied, "Now, come. I do not wish to lose you again."
Arrietty followed him but turned around and winked at Merlin. She thought she knew how to save Sir Ewen.
Not knowing what else to do, Merlin ran into Arthur's chambers."
"What are you doing here?" Arthur demanded, "Where is Arrietty?!"
"Something went wrong." Merlin began, "He's got Arrietty."
"Who had Arr- "Arthur began, then his voice trailed off, "Valiant?"
"Yes." Merlin replied, "And it gets worst. You know Sir Ewen, the knight he thought today that was injured?" Not giving Arthur the chance to answer, he continued, "Well, I've just seen one of the snakes on Valliant's shield come alive, me and Arrietty we both did. He's using magic."
"What do you mean?" Arthur asked.
"I mean one of the snakes came out of his shield and ate a mouse." Merlin elaborated, "One swallow, straight down. Sir Ewen was fighting Valiant when he collapsed. It must've been one of the snakes from the shield."
"Alright, not to sound selfish, but how does this lead to him getting his paws on—" Arthur's voice trailed off, "Good Mother, he didn't—"
"He didn't catch her in the act." Merlin assured her, "She just came out to throw him off. As far he knows, she was just out doing her own business."
Meanwhile, Arrietty was sneaking through Vaillant's chambers again, to where the shield was kept. After looking around to make sure no one was about to catch her in the act, she grabbed it, winching. When nothing bit her, she ran for it.
"We need to get her out of here." Arthur declared for the second time in as many days, heading for the door, "Now."
"But what about Sir Ewen?" Merlin asked, "We have to find a way to get him an antidote."
"Give me minute." Arthur said, running his fingers through his as he paced the floor. But they didn't have a minute. He had to act now.
Meanwhile Arrietty was running through the halls, hiding the purloined shield under her clock. She was so frantic she bumped right into a young woman, about the same age of Merlin and her brother, with her dark curly hair done up on her head.
"Sorry." Arrietty said, backing up.
"It's alright," Guinevere assured her. After a beat she asked, "Are you alright?"
Arrietty nodded: "But I'm looking for someone. He's about yeah, high dark hair, big ears, name's Merlin."
"Oh," Gwen responded, "I just saw him going into the princes' chambers…"
"Thanks!" Arrietty exclaimed, taking off again.
Arthur was still pacing the floor when suddenly Arrietty burst into the room. "I did it!" She declared.
Did what? Arthur sighed, truly scared of what the answer would be at that point.
For an answer, Arrietty dropped Valliant's shield to the ground.
Have you lost your mind?! Arthur signed franticly.
It's probably not what you think. Arrietty replied quickly, The snakes on the shield are alive. We saw Valiant take am mouse and—
A snake came out and ate it. Arthur cut her off, I know, Merlin told me.
Oh. Arrietty replied, except she just made the sign for the letter. It still got what she meant across. After a beat she added, Well, we can't let him keep it, what if you make it to the end? I can't let him use it on you.
Alright. Arthur conceded, But it makes this official. We have to get you out of here now! Then she pushed him towards Merlin saying, "Valiant still might report his shield missing. You need to get her out of here."
"What about— "Merlin began.
"I don't know." Arthur cut him off, "God forgive me, but I don't think we can help him."
Suddenly it occurred to Merlin. "I can." Then he picked up the shield, took Arrietty by the wrist and ran out of the room.
"Merlin?" Arthur responded stepping out, "Merlin, what does that mean?! MERLIN?!"
Merlin ducked off into the nearest room, turning Arrietty around. She quickly turned herself back around, but fortunately not soon enough to see Merlin cast the spell.
She did, however, turn around in time to see a snake slithering out of the shield, posing to strike.
Arrietty screamed just as Arthur ran into the room sword in hand. Taking swing, he took the thing's head off. The other on came out, but he didn't see it. Merlin picked up a nearby sword and swung. Managing to decapitate the creature as well.
"Nice hit." Arthur said before leaning down and picking up a head, "I'll get this to Gaius, now just go. "
Merlin didn't have to be told twice. He grabbed Arrietty who grabbed the shield and the pair ran out the castle, through the city and into the forest.