This was written for the After Camlann Big Bang challenge 2018 on LiveJournal.

FULL SUMMARY: There's a new witchfinder in Camelot. He's younger but smarter, more dangerous and hell-bent on hunting down a sorcerer called Emrys. Fearing the worst, Merlin flees and leaves Arthur only with a letter. But Arthur, being as stubborn as ever and not liking the idea of Merlin out there alone, sets off after him, finding out more about his servant and friend than he'd ever wanted to as a result. Not only must Merlin and Arthur learn how to be friends again, but also how to work together and get rid of the witchfinder, who's meant to stay by the king's side forever. Especially after he finds out who Emrys is and where he's hiding.

IMPORTANT: Unfortunately, I can't post all the art here on FFN, so if you want to see it, head over to ao3, where this fanfic is also posted. Especially chapters 1, 3, 4 and 9 have art in them. The link to ao3: archiveofourown (dot org) /works/15992399/chapters/37310783

AUTHOR'S NOTE: I started writing this back in November 2017 as a NaNoWriMo project, and it took a long time, but it's finally finished!

This was my first ACBB and it was fun! I think that without the deadline I'd never even finish this fanfic - I dealt with it like with any other deadline in my life - I ignored it for half a year and then finished everything on the last few days. Finding a beta was definitely a challenge, too, but then I found two that helped me a lot to get everything done in time - thank you so much Savannah and Jetainia! And another thanks to Sacred Cakes for doing your best, even though the universe was apparently against us. While finding a beta was a challenge, finding an awesome artist was not - I love the art and I want to thank matchboximpala for picking my story! It was messy and as I later realized, full of grammar mistakes, but you were willing to read it anyway. And thanks so much for being ok with me wanting to include my awkwardly drawn maps in the fanfic too! :D

Without further ado, enjoy the fanfic! :)

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CHAPTER 1

The Secret Goodbye

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One little push on the door with his knee and he was in – closing the door behind himself again, he balanced the tray full of food on one hand as he entered the chambers. One, two, three steps to the table where he carefully set down the tray, and he could finally glance up at the prince's bed just like he did every morning - only his gold hair was visible from this angle.

Merlin smiled.

"At least he's not snoring today - hah, lucky," he mumbled to himself, cheerfully arranging the food on the tray. (That apple had not fallen down the stairs on his way up from the royal kitchen!)

At that moment, Arthur tossed in his sleep and let out a very loud snore.

Merlin smacked his lips and rolled his eyes. "Not so lucky after all," he whispered, shaking his head. But once he was done with the food and turned towards the bed, he couldn't help but smile again. Arthur was now facing him, expression peaceful and mouth (thankfully) closed. He looked so handsome . . . just like he did every morning. Well, maybe unless his mouth was wide open.

Merlin smirked and closed his eyes, taking a deep breath in preparation for Arthur's usual attitude right after he had been woken up. He rounded Arthur's bed to get to the window, which he opened to let the cold air into the room along with some light. For a moment, the orange, red and yellow trees' crowns and leaves on the ground caught his attention. The road to the castle wasn't empty. Someone was coming to Camelot. A guest.

Merlin knew this because that's exactly why he had to wake Arthur up a little earlier today. Someone was here to visit the king - which meant that both he and Arthur, as well as Gaius, had to be there, all dressed and fed. Merlin chuckled as he remembered that one time Arthur's stomach had growled so loud that everyone in the throne room had heard it.

But if he didn't want that scenario to repeat, he had to hurry up. He was already a bit late, judging by the said guest that he could still see from the window.

Merlin turned to Arthur again and grinned. "Rise and shine!"

Arthur groaned and rolled even farther away from him, mumbling something unintelligible into his pillow.

"Come on, Arthur," Merlin tugged at his blanket, slowly pulling it away. He knew that it felt like torture to Arthur on cold mornings. "You have to meet your father's guest today."

"Kaunos?" Arthur's eyes went wide in a fraction of a second (much faster than Merlin ever remembered seeing), and then he closed them again in regret. "I completely forgot about that!"

"Yeah, well, that's why I'm here," Merlin shrugged with a smile.

"And that's also why I'm going to be late. Again."

Merlin frowned at that. "How can you tell I'm late when you haven't even properly woken up yet?"

"Because I know you, and you're incapable of getting here on time," Arthur answered and rolled his eyes, throwing his legs over the edge of his bed.

Maybe Merlin hadn't prepared himself for Arthur's attitude enough.

"Prat," Merlin cleared his throat loudly and went back to the window, just to open it a little wider.

"What did you say?"

"Just that I think I finally caught that rat, sire."

"What rat?" Arthur turned to him, looking confused and also not very convinced that Merlin was telling him the truth.

"The one that isn't here anymore," Merlin smiled. "Now, let's get you dressed." And without another word, he walked to the other side of the room, where he'd prepared Arthur's clothes for this morning's meeting the day before.

Arthur seemed to let the comment about the rat go as he finally stood up and headed for the changing screen. Not that he used it much anymore, Merlin noted. Lately, he liked to change his clothes wherever in the room he was, not really interested if Merlin saw him or not. And Merlin tried hard to pretend like it was no big deal, but honestly? He's found himself staring at least a dozen times already.

"Here," he handed Arthur his best red tunic and watched as the prince took off the white one that he was sleeping in. Merlin had admitted to himself a long time ago that he missed the days when Arthur used to sleep with his bare chest, but the summer was gone and the days were cold in this time of the year. And he couldn't possibly let Arthur catch a cold, he'd never hear the end of that.

The prince accepted the red tunic and put it on, already getting out of his loose trousers. Merlin swallowed and looked away, starting to count the candles on the several candelabra on a little table in the corner of the room - sixteen, it's always sixteen - but eventually glancing at Arthur anyway. He was just putting on the trousers that Merlin had handed him and- wait, was that a smirk? Did Arthur just smirk at him? Oh god, did he know this entire time that-

"Do you have better clothes for yourself or are you going to embarrass the entire royal household in front of our guest today? Again?" Arthur turned to him, the smirk suddenly gone. (But Merlin could still see it there, almost . . . or was he just being delusional?)

"Wha- no, I thought I'd go in this," he cleared his throat and looked down at his clothes. Without any warning, Arthur reached for the hem of Merlin's blue shirt and felt it between his fingers, making a displeased face. Merlin knew that face very well. "Oh n-no," Merlin jumped away from him, his hands in front of him. "I'm not putting on that ridiculous attire for Camelot servants ever again!"

Arthur only laughed, "I was joking."

Merlin wasn't entirely convinced though. "You know what? That apple that you're about to eat for breakfast fell down the stairs and hit every step on its way down." Arthur frowned at him. "I was joking," Merlin shrugged and walked away with a satisfied smirk.

"I hope you are," he heard Arthur mumble as he followed him to the table, where the breakfast awaited him.

There were times when Merlin was almost sure that Arthur knew Merlin was in love with him. Like this morning, for example. But then there were times when Merlin was convinced that Arthur didn't have a clue. Merlin knew one thing for sure - there was something between them. And not just destiny, or friendship - there was something else, something that he hoped Arthur would recognize one day. But until then, all he could do was hope.

Filling Arthur's goblet with fresh water, Merlin watched as Arthur started on the ham and cheese, suspiciously eyeing the apple. Then he finally went to close the window, start the fire in the fireplace, and collect Arthur's dirty laundry, avoiding the socks as much as he could.

"The meeting with your father starts in about twenty minutes," he told Arthur, who was still sitting at the table on the other side of the room.

"Don't be late," Arthur replied.

Merlin just rolled his eyes, this time fondly. "Am I ever?" he whispered to himself. How many times had he already saved Arthur? And was he ever too late for that?

He picked up the basket full of Arthur's tunics, vests, trousers, socks and underwear, balancing it underneath his arm and against his hip. With his other hand, he reached into one of the closets and retrieved a dark brown vest that he'd also prepared the day before. Then he went back to Arthur and put the vest on the table, grabbing the basket with both his arms.

"It's cold out there," he explained with a smile.

"I swear I heard concern in your voice."

"You definitely didn't."

Merlin smiled innocently at him and turned to the door only after Arthur returned the smile. In the next moment, he was already rushing down the stairs.

He needed to not only get rid of Arthur's dirty socks (and other clothes) but also get back to Gaius' chambers and change into . . . Something better. Maybe his other red tunic? Or a blue one? What would Arthur appreciate more? And would he even notice?

Before he knew it, he was already on his way back home to the tower. He ran up the stairs and opened the door.

"Gaius?" The old man was sitting by the window, his head turned away from the young warlock. "What do you think suits me better? The red tunic or the blue one? And I know it's cold, so I should probably keep the neckerchief, but do you think Arthur would- Gaius?"

The physician had turned to him while Merlin was speaking and he didn't look happy at all. He looked as if something terrible had happened – as if it was now his job to deliver the awful news. His lips were a tight line instead of the smile that Merlin had expected and his eyes were sad.

"Gaius?" Merlin repeated, hundreds of ideas about what could have possibly happened already swirling through his head.

"Merlin, I need you to listen to me." Gaius stood up and walked over to the warlock.

"Wha- is my mother alright?" That was the worst of all the thoughts that Merlin had.

"Hunith is alright. This is . . . something else."

"Then what is it?"

"The new guest-"

"Kaunos?"

"Yes," Gaius nodded. "What do you know about him?"

Merlin shook his head. To be honest, he hadn't thought about him much at all - he was just a guest that was coming to visit the king. Maybe because he and Uther knew each other?

Gaius took a deep breath before he said what he needed to. "He's . . . a witchfinder."

Merlin took a step back and let the information sink in. Kaunos was a witchfinder. Another witchfinder. Why would Uther send for another witchfinder after what happened the last time? After what he did to Gaius? Had he seen signs of magic again? Was it all Merlin's fault?

"Merlin?"

Merlin took a deep breath when he realized he'd stopped breathing altogether. "This isn't happening." He shook his head and without him being able to stop it, his eyes filled with tears. "Gaius, tell me this isn't happening!"

Gaius closed his mouth - a thin line again. No smile.

And just like that, Merlin's world crumbled around him.

"You need to leave," Gaius continued.

"What?"

"Merlin, listen to me." Gaius walked over to him and gently took his shoulders. "The witchfinder is going to stay in Camelot until Uther is sure that there isn't anyone with magic living in his kingdom. He can't find out about you, that's why you need to leave and return when it's safe."

"But . . . but what about you?"

"I'll be fine," Gaius smiled at him. This wasn't the smile that Merlin wanted to see - it wasn't at all reassuring.

"I can't leave you here, Gaius."

"You must." His smile disappeared again. "Uther came here to tell me who Kaunos is in person. He said that he wouldn't attempt to interrogate me again." And before Merlin could say anything, Gaius enveloped him in a hug. "You must leave as soon as you can. No one can see you at the meeting either."

Merlin hugged him tightly and nodded against Gaius' shoulder. "I'll leave," he mumbled. Gaius nodded as well and let go of him.

"I need to go to the meeting."

Merlin nodded.

"Good luck, my boy."

"I'll miss you," Merlin brushed away his tears as he took a few steps closer to his room.

"You'll see me again, sooner than you think," Gaius smiled at him. Then he finally left the room and Merlin only heard his footsteps as he descended the stairs.

"Not soon enough," he sighed, his voice shaking.

Ten minutes later, and Merlin had already packed his red tunic, one extra neckerchief, thick socks and trousers. He didn't forget about his spellbook that couldn't be found in Camelot, especially not with a witchfinder searching through every home, and he even took the little wooden dragon that his father had given him.

Looking at that little toy made his heart ache. His father died only five months ago, but it still hurt so much that he occasionally had nightmares about it. But he couldn't think about that now. The meeting was about to start in a few minutes and he needed to be gone once it was over.

At least Morgana wasn't here to go through this all over again. They still hadn't found her after she disappeared with Morgause. Merlin never stopped feeling guilty about it. If only there had been another way to save Camelot . . .

But that was another thing that Merlin couldn't worry about right now. He stuffed the book and the little dragon (together with the rest of the breakfast Gaius had made him that morning) into his backpack, and with one last look, he left his room.

There was only one thing that he had to do now.

xoXÖXox

The halls were just as cold as the wind outside. It certainly wasn't the most pleasant weather. Most of the people working in the castle were either inside one of the many castle chambers by a fireplace or already in the throne room, awaiting the guest - so now the only thing Merlin had to worry about was where to go after he said his goodbye.

He had no idea which direction to go or what to look for out there. He'd thought about going back to Ealdor (it was only for a few days or weeks, wasn't it?) to let his mother know what had happened. But that was the first place everyone would go look for him if they thought he was running away. He couldn't go back there - he had to find a new village. And since the only person stubborn enough to follow him anywhere was Arthur, he had to say goodbye without him or anyone else knowing.

Through a letter.

It shouldn't be too hard. He's written way too many speeches for Arthur over the three years that he's been working for him.

Except that this was hard. He was about to say goodbye to the man he hoped he could stay with every day of the week no matter how bossy he was. That was something Merlin still couldn't wrap his head around. How could he have fallen in love with him? But he wouldn't change that even if he could. He'd never change that because falling in love with Arthur made his days in Camelot infinitely more bearable and enjoyable.

No matter how bossy Arthur could be.

Merlin took a deep breath and turned another corner, heading for the stairs that led to the floor where Arthur's chambers were. He told himself it was the cold air that got into his eyes, but the tears on his cheeks were proof that it wasn't.

It was only for a few days, maybe weeks. He could stay away from Arthur and Camelot for that long.

But could Arthur stay away from him? If the letter he was about to write was to be believable, Arthur shouldn't worry about him. He should just accept it and wait for his return. But if he didn't believe what Merlin wrote, he'd surely go searching for him into the forest or Ealdor and get himself killed somewhere along the way . . .

Merlin closed his eyes and shook his head. He really had to stop thinking about things like this.

Arthur managed to survive the first twenty years of his life without Merlin there by his side. What could a few more days (or weeks) possibly do to him?

The young warlock finally reached the last flight of stairs and looked up at the corridor that led to Arthur's chambers. The meeting had already started and Arthur was supposed to be there right next to the king, so Merlin didn't worry about accidentally running into the prince in his chambers. What he didn't expect though was someone else, standing on the upper end of the stairs with a basket in her hands as she looked down at him.

Gwen.

Merlin breathed out and his eyebrows knitted together slightly. He had hoped he wouldn't meet anyone, but at least he could say goodbye to her as well.

"Merlin," she spotted him on the bottom of the stairs and gave him a sweet smile. That smile disappeared though as soon as she got a closer look and saw how distressed Merlin looked. "What happened?"

"Gwen," Merlin barely smiled and rushed up the stairs to meet her halfway. As soon as she was within arm's reach, he pulled her closer to him, careful not to knock the basket out of her hands.

"Merlin? What's wrong?"

Merlin couldn't tell her. He didn't even know what he'd tell Arthur once he had a quill in his hand and a blank sheet of paper in front of him. Besides, the real reason for why he was leaving had to stay a secret. As always.

"Nothing," Merlin sniffled and closed his eyes briefly. Then he pulled back and regained his composure. "Please don't follow me."

"But-"

"Please," Merlin looked into Gwen's eyes but didn't wait for a nod. He couldn't tell her anything and he had to leave Camelot as soon as he was done with the letter. Once he returned, he could make up something to tell Gwen. But right now? She couldn't know.

Without another word and with a hopefully reassuring smile that he managed to give her, he ran up the stairs and disappeared in another hall. He didn't look back as he ran to Arthur's chambers, but he didn't hear any footsteps behind him anyway. Gwen was a good friend and a woman of her word.

As soon as Merlin reached the doors, he wrenched them open, stepping into the room and leaning back against the once again closed doors behind him.

In front of him was Arthur's table, with candles and a pitcher full of water resting on its surface. In the corner, the fire he'd started earlier was still burning - the last bit of warmth he was going to get until he was safe in the forest or a cave somewhere, and could start a fire of his own.

Merlin sighed and walked over to Arthur's writing desk. He let his backpack fall down to the leg of the table as he lowered himself down onto the comfortable chair. Picking up Arthur's quill and moistening it with ink, Merlin chose a sheet of paper from the pile sitting on the corner of the desk.

With a heavy heart and a trembling hand, he began to write.

Dear, Arthur.

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At the end of most of the chapters, there's a list of spells that I used/created, or some notes :)