Arthur should have listened to Merlin. Though he would never admit it, there were many times in his life that he regretted disregarding Merlin's little cryptic warnings and 'bad feelings'. But he had never regretted it as much as he did now.

A villager had journeyed to Camelot to report sightings of strange green lights coming from a cave near his village. He claimed that when a group of the braver villagers had gone to investigate they had been attacked by a strange creature the likes of which they had never seen before. This creature killed two of the villagers before finally being taken down.

Of course Arthur had agreed to investigate himself, along with a group of his best knights and (although this went unsaid) his personal manservant. And, of course, he wanted to leave immediately, which led to Merlin rushing around, trying to pack for both himself and Arthur, which included restocking his bag of medical supplies, getting the horses ready, getting Arthur ready and also trying to make time to see if Gaius would recognise the description of the creature.

"Are you sure you've never heard of anything like it before?" Merlin almost tripped down the stairs from his room as he asked the question, his spare clothes falling from his hands as he grabbed onto the wall to steady himself.

"I'm sure," Gaius responded. He was quickly flipping through the pages of one of his books, looking for any information. "If only you all weren't in such a hurry to leave, I might've had a better chance to find something."

Merlin brought his things over to the table Gaius was seated at and started packing it all into his bag. "And you haven't been able to find anything about green lights either?"

"I'm sorry Merlin," Gaius sighed. "I wish I could be more help, I really do."

"It's alright Gaius," Merlin smiled at the old man. "I've gone into dangerous situations with less knowledge than this. At least that villager warned us about its ability to move from one place to the next in an instant."

Merlin finished packing and hefted the strap of his bag over his shoulder.

"I should get going," he said.

Gaius walked over to him and placed a hand on his shoulder.

"Be careful Merlin," he said. "Come back to me in one piece."

Merlin smiled at Gaius, who he knew worried about him as a father would worry about their own son, and pulled him into a hug.

"I promise."

It was a good day for travelling, warm, with a cloudless blue sky above. Unfortunately Merlin wasn't able to enjoy this, his mind stuck on what lay ahead. Though he acted brave in front of Gaius it did bother him, not knowing what they were going up against.

Merlin was so caught up in his own thoughts and worries that he didn't notice the intermittent glances that Arthur had been sending his way for the last several minutes. Finally Arthur huffed and slowed down his horse till he was beside Merlin.

"What's wrong with you now, Merlin?" he said, causing Merlin to startle and give Arthur a questioning look. Arthur rolled his eyes. "Don't play dumb, you know what I mean. You've spent the whole day looking as a man does on his way to the executioner's block."

"Considering how little we know of what we're walking into we could be," Merlin retorted.

"Merlin, mate, you worry too much," Gwaine's voice comes from his other side and Merlin turns to frown at him.

"I worry just the right amount! That creature killed two people and we know next to nothing about it," he said. "If it can move from one place to the next in an instant who knows what else it might be able to do."

Arthur scoffed. "You're forgetting that those men were farmers and we are knights with all the training and knowledge that goes along with the position."

Percival twisted around on his horse to grin back at Merlin. "If anything happens we'll protect you Merlin," he said, earning a few chuckles from the other men.

"See?" Arthur said smugly. "Nothing to worry about."

He nudged his horse to go faster so he could take his place at the front of the group, leaving Merlin alone to stew in his annoyance. Not for the first time, he wished he could tell the others that he had magic. That more than likely he would be the one protecting them. That maybe they should listen to his concerns instead of dismissing him and seeing him as just a frightened servant.

As they approached the cave conversation fell to a hush. They could all see the eerie green glow emanating from within. Merlin swallowed nervously but dismounted with the others. There was an air of tense anticipation as they tied their horses to nearby trees, and gathered together near the cave's entrance.

"I want everyone on high alert from here on out," Arthur said. "Stay quiet, keep an eye out for anything strange. And," He glared at Gwaine and then at Merlin. "No mucking around. This is serious."

Gwaine snorted and rolled his eyes. "It's like he doesn't trust us," he muttered to Merlin.

"I wonder why," Merlin grinned. Gwaine shrugged and tried his best to look innocent and Merlin laughed, which caused Arthur to turn and glare at them again. Merlin and Gwaine both gave him wide eyed looks and he just sighed and entered the cave.

Merlin and Gwaine grinned at each again before following along after the king.

There was something wrong in the cave, something that Merlin couldn't quite name but left him vaguely nauseous, his heart jack-rabbiting in his chest. It was almost like the world was thinner here, not as real as it was outside and it made Merlin want nothing more than to leave this place and never return.

"Arthur, I don't like this," Merlin said, reaching out to grab onto the sleeve of Arthur's shirt, as if that would stop Arthur from running off into danger as he always did.

Arthur shrugged Merlin off and gave him an exasperated look.

"I'm aware," he said. "And I was aware the last time you said, and the time before it. Go wait outside the cave if it's bothering you that much."

Arthur continued to lead the way into the cave and the knights followed, Gwaine patting Merlin reassuringly on the shoulder as he passed. Merlin let out a loud sigh and made to follow when-

"Someone, help me."

He froze.

The woman's voice had echoed through his head, similar to when a druid spoke to him through his mind. A quick look at where the knights confirmed that only he had heard her. Merlin reached out with his magic, trying desperately to figure out where the call had come from.

The knights continued onward, unaware that they were leaving their friend behind.

The cave path eventually opened up into a cavern and everyone's attention was drawn upwards where a swirling mass of sickly green mass was floating in the centre of the cavern. Gwaine tightened his grip on his sword as the others slowly drew nearer to the unearthly glow.

"Bet this is the strangest thing we've seen yet, hey Merlin," Gwaine said.

There was no reply. Gwaine frowned and turned around. There was no one behind him.

"Merlin?"

Gwaine had only taken a single step back in the direction they had come from, the mission unimportant compared to the safety of his friend, when there was a loud crack behind him accompanied by shouts of alarm from the other knights and he spun around, heart hammering from the sudden shock. The glow in the centre of the cavern had changed, contracting in tight, now resembling some kind of amalgamation of sharp jagged rocks. Not that Gwaine really cared, his attention instead drawn to the creatures that had appeared in the cavern, seemingly out of nowhere.

There were three of them and they were just as the villagers had described them. Tall and spindly, their limbs branchlike in appearance, their faces almost looking like they had partially melted down towards their emaciated chests. While Gwaine stared one of the creatures seemed to fall into the ground, disappearing from view. The hair on the back of his neck prickled and it was only due to years of experience on the battlefield that Gwaine was able to spin around in time to block the blow from behind him as the creature lunged out of the ground.

It now stood between Gwaine and wherever Merlin was and he snarled, kicking out, his boot connecting with the creatures midriff, knocking it back. There was the sound of battle cries from behind Gwaine, the metallic clash of swords, and Gwaine let out a shout of his own as he lunged forward with his sword.

There was a side passage that they had originally missed, so intent they were on finding the source of the green glow, and Merlin slipped inside. The side passage seemed to run parallel to the main passage so the strangeness of the atmosphere continued to grow stronger, though perhaps not as strong as it would if he had continued with the knights. Somehow Merlin knew this was where he needed to be.

It felt like the air should be thin, Merlin should be struggling to draw a full breath, but that wasn't it. No, it was magic, strange and unfamiliar, all around him. The pleas for help echoed in his head again and he reached out with both hand and his own magic, and then-

Everything was green.

Everyone who knew Gwaine knew that he loved to fight. When he was fighting he was able to give into that rush of adrenaline, the thrill of meeting a worthy opponent and coming out victorious. But this was different. There was something about the way that creature moved, the chilling shrieking sound it made that left Gwaine with goosebumps, his knees just barely trembling. But he couldn't falter, not when Merlin could be in trouble.

There was a flash of claws, slashing down towards his face and Gwaine lifted his sword and braced himself, his arms shaking with effort as claws clashed with sword, making a discordant metallic screech and the creature pressed it's attack, that horrifying mouth open wide and moving in closer to Gwaines' face-

Then a familiar burly body came in from the side, as Percival rammed his sword through it's middle, his momentum carrying himself and the creature into a sprawling heap on the floor.

In a single swift movement Percival rolled away from the creature and sprang back to his feet, standing at the ready, Gwaine already at his side to support his friend but- But the creature hadn't gotten back up. In fact it seemed to be disintegrating right before their eyes. Not phasing through the ground like it had done before but actually fading away into thin air till there was nothing left but some small bits of debris on the ground where it had lain.

Gwaine and Percival shared a bewildered look before turning to the battle behind them.

There was only one of the creatures left, and Arthur, Leon and Elyan were surrounding it. Elyan charged, stumbling as it quickly dropped through the ground, and they all looked around, waiting for it to pop up again. Gwaine noticed the beginning of a green swirl on the ground behind Arthur and yelled.

"Arthur!"

The king spun around, thrusting outwards with Excalibur. There was a screech of pain and it also faded away into thin air.

The green glow in the middle of the cavern contracted again, bursts of green striking out, hitting the ground, forcing the knights to back away. There was another loud crack, this time with an explosion of sickly green, and a burst of air that threw everyone off their feet.

When it was safe Gwaine sat up, looking back to the centre of the cavern, expecting there to be more creatures. But there was nothing. The green light was gone.

"Is everyone alright?" Arthur called out, pushing himself to his feet.

"I'm uninjured," Leon said.

"Same here," Percival said.

"I'm fine asides from the giant bruise I'm going to have on my ass come morning," Elyan muttered.

"Great!" Arthur grinned proudly. "Looks like that's done it."

Gwaine rolled his eyes at Arthur's preening and turned his attention to more important matters. Namely, Merlin. "In case you haven't noticed princess," he said, Arthur bristling as usual at the nickname, "but Merlin's missing."

Arthur tensed, then scoffed. "He's probably off hiding somewhere like he usually is." But none of the knights were fooled, they knew Arthur well enough to see the hidden concern in his eyes. "Spread out, we'll find him and let him know it's safe to come out."

There wasn't much of the cave to search. Only one side passage which led to a dead end. Yet Merlin was not there. Arthur was not worried. He stormed out of the cave, the stomp of his feet echoing satisfyingly from the cave walls and did a quick cursory look of the surrounding forest.

Then he drew in a deep breath.

"MERLIN!"

A few birds flew out of the trees as his bellow scared them away.

Merlin, that disobedient idiot, did not show up.

Arthur was not worried.

"Split up," he said to the knights. "He probably got distracted and ran off after a butterfly or something."

They searched till the sun slipped below the horizon. There was no sign of Merlin. No tracks, which was unusual. Merlin, as clumsy as he was, always left tracks. He wasn't skilled in hunting and stealth and not falling over his own feet like Arthur was.

"Arthur."

It was Leon, standing a respectful distance from his side.

"It's getting too dark to see. Perhaps we should stop."

"Not until we've found him," Arthur ground out, "and I've told him exactly how long he'll be spending in the stocks."

"For once I agree with the princess," Gwaine said.

Elyan shook his head. "We couldn't find any tracks or signs that could point to where he went when it was daylight, how are we going to find anything in the dark?" he said, and Arthur hated him a little for being so reasonable.

"We could go to the nearby village," Percival said. "Maybe he went there, or maybe the villagers know where he could've gone."

"Fine," Arthur said. "We'll look for him there."

They set off in the direction of the village, and Arthur felt a bit lighter than he did before. Of course Merlin would be in the village. He'd probably run off to the village at the first sign of danger. Arthur ignored the little voice in his head that said Merlin would never run away from danger when he could be throwing himself right at it in some misguided attempt to protect his friends. He ignored every instinct that told him that something was not right, that something had gone very wrong.

Arthur. Was not. Worried.