This is a parody of the SpongeBob episode "The Secret Box" combined with Merlin. This takes place in the first season.
"Merlin!" Arthur screeched from his room. "MERLIN!"
"I'm right here, sire. If you just waited a little bit you wouldn't have to yell so loudly."
"What's that you got in your hands?" Arthur asked gesturing to the large, brown box he was holding.
"Oh, this?" he responded while pulling the box closer to him. "It's nothing."
"If it was nothing then you wouldn't be holding it so close to you."
"What is it that you called me for?"
"Don't try to change the subject, Merlin."
"Why would I want to change the subject to work?"
"Because whatever's in that box is important," he angrily said reaching for the box.
"Well, it's a secret box, so you can't look inside of it," Merlin said leaning away from him.
"Give me the box!" Arthur demanded.
"NO!"
They both were now wrestling on the ground for it. It flew out of Merlin's hands and went slide across the room. Arthur shoved Merlin's face back and leapt towards it as Merlin used his magic to have it slide away from Arthur who ended up slamming his face on the ground. Merlin then stepped over him, grabbed the box, and said,"Well if that's all I will be going."
Later that evening
Merlin was walking back to his and Gaius's quarters when Arthur caught a glimpse him and called out his name. Merlin slowly turned around and saw the young prince walking towards him. He wanted to somehow escape with his box, but there was nowhere to go and he had already made eye contact.
"Merlin, I'm sorry about earlier, but what is in that stupid box that you are so protective over?"
"Nothing you need to be concerned about," he spat. "You're the prince; don't you have more important things to do?"
"Not today," Arthur said shaking his head. "Why won't you show me what's in it?"
"Why would I? I don't know any of your secrets."
"That's because I don't have any."
"Really? What about every single day when you never answer any of my questions?"
"Well, that's different. Those are secrets that might put Camelot in jeopardy."
"That's not what I'm talking about," he sighed.
"Then what are you talking about?" Arthur yelled back.
"I really don't know that much about you," Merlin answered almost unsure of himself.
"Merlin, you've worked for me every day for almost a year. How is it possible that you know anything about me?" He then lowered his voice and said, "Maybe you're even more of an idiot than I thought you were."
"You see that's why I don't know anything about you," Merlin explained annoyed. "Every time I ask you a personal question you get offended and call me an idiot."
"I do not get offended!" he said offended. "What do you want to know?"
"I don't know… Anything."
"Okay, but if you tell anyone this I personally throw you out of Camelot."
"Understood."
"Okay… well I've never-how should I put this- I've never really-"
"Just spit it out!"
"I've never kissed a girl," Arthur muttered, blushing.
Merlin tried to contain his laughter by covering his mouth, but it still got through. Arthur seemed to be trying to kill Merlin with his glare as Merlin collected himself and said,"I'm sorry, but it's just too good. The high and mighty prince of Camelot hasn't even kissed a girl. Not to mention that's his only interesting secret."
"Like you've done any better."
"Actually, I have," Merlin said still laughing, "couple of times."
"This is why I don't tell you any of my secrets. Now give me the box."
"No."
"What did you say?"
"Well I was hoping that your secret would be as good as mine, but now I see it isn't anywhere close."
"A deal's a deal."
"Nah."
"Don't you have any honor?"
"I didn't think servants were supposed to have any," Merlin said as he walked into his chambers leaving Arthur more frustrated than he had seen him up to this point.
Later that night
Arthur was tossing and turning that night, unable to get to sleep. Why was that damn box bothering him so much? He had never known Merlin to have the ability to keep any secret, even the smallest of the small. So how was he able to keep this one? It must be important. What if he had some sort of magic that he was going to use to curse him? No, Merlin's not that smart. What if Merlin was a traitor and had some valuable pieces of information in there? But Merlin had saved his life so why would he? What if he held records of everybodies most embarrassing stories to use if he ever need to blackmail someone?
'I can't take this!" Arthur thought while jumping out of his bed. He put on a shirt and a pair of books and then snuck over to Merlin and Gaius's rooms. Once there he silently opened the door, slide in, and ,without so much as a creek, closed the door. He easily walked past the deeply sleeping Gaius, but the real trouble came when he got to Merlin's room. His door was creaked at the slightest touch. It seemed to be several times louder than it was during the day. So he quickly pushed through the door and found that doing this would cause it to make no noise. He looked around in Merlin's room for that large, brown box, making himself feel foolish while doing so, but then something wonderful happened: he saw it.
The box was sitting right next to him, on the little night stand he kept beside his bed on the far side. He started to lunge towards it but found himself tripping over a book. BAM! Arthur looked up to try to see if Merlin had awoken, but he had only slightly stirred and started muttering some random crap. Arthur soon saw that Merlin's room was as dirty as ever, riddled with books and clothes. Now this made Arthur want to know what was inside that box even more. This was just another obstacle he had to overcome to complete his quest, a most noble quest if ever there was such a thing.
With great stealth, or at least Arthur thought so, he maneuvered through the minefield of Merlin's room. Every step seemed as though it should have woken Merlin up, but no matter how much noise the prince thought he made the brunette never woke up.
Finally he reached the object of his quest: the secret box. He had grabbed hold of it and was about to open it when he sneezed. This, out of all the noise Arthur had made, had woke Merlin up. Once the young brunette's vision cleared and he saw the prince being caught red handed with his special box he really didn't know what to think.
"Arthur," he began drowsily. "Have you gone mad?"
"Look, I couldn't sleep, and I just need to know what's in this damn box," the prince whined.
"I thought we were friends. I thought we could respect each other's secrets. That's why I only made you tell a little one like never kissing a girl. I could have guessed that. I thought it was understood that friend don't pry." With saying this Merlin looked so sad and childlike that Arthur seemed to have no other option.
The blond sighed, held out the box, and said,"Here. I didn't mean to hurt your feelings."
Merlin looked up from his pouting, smiled, and said,"I was only joking. You can look inside if you really want to."
Arthur wanted so badly to smack him at this moment, but his curiosity of the box was too great. He took one more look at Merlin, and then open the surprising heavy brown with excitement in his eyes.
"A-a-a string?" Arthur choked out puzzled. "You've been guarding this stupid thing all day with your life, and IT'S JUST A BLOODY STRING?"
Merlin was dying laughing on his bed. Arthur wasn't even sure if he could hear him.
"How is this funny?!" Arthur roared. "It's just a string. You know what, no. I should have known. I'm going to bed." He then proceeded to slam the door and storm back to his chambers. "What a simpleton. I should have known that it would be nothing."
"What was that about?" Gaius asked surprised.
"Arthur looked into my secret box, saw the string, and thought I was a complete simpleton, but if only he pulled the string." Merlin started to yank the string up and with it came the bottom of the box. He pulled out what looked like a charm of the old religion and several pieces of paper. "This is a charm that makes people reveal their secrets without realizing it, and these are the papers I record them down on. You see while Arthur thought he was only telling me a small secret, he doesn't realize that throughout the day him and others have been shouting all of their bigger more interesting ones."
Gaius just stood half asleep and half mortified looking at Merlin. "That has to be the dumbest thing I've ever heard," he said rather dryly. Then he snatched the box with all its contents away from Merlin. "Goodnight Merlin."
"Goodbye, my secret box."
Fin