That was quite a response to the last chapter! Thank you so much to everyone who reviewed, followed and favourited - Sorry I can't reply in PMs to the guest reviews - I love hearing your comments.

A big shout out to Caldera32 for her tireless work as my Beta.

So here is the next chapter – Merlin's health starts to deteriorate and Arthur begins to realise what he has done! Hope you enjoy it. As always your thoughts and views are welcome and very much appreciated.

Chapter 5 The Potion Takes Effect

By the time Merlin reached Arthur's chambers his vision had started to blur slightly, but just as he got worried about it his surroundings came back into sharp focus. The warlock's brain banged like an incessant drum and he struggled to balance and place his feet. He was clumsy at the best of times but he'd never felt like this – something was seriously amiss. The sorcerer tried to think of a way to improve his situation but it was hard to concentrate and formulate an appropriate spell. He stopped, bracing himself against wobbly knees, trying and failing to get his head together. He let his forehead rest against the cold stone in a vain effort to ready himself for the task ahead, but he could not put it off any longer. He grasped the handle and pushed the oak door open, ready to greet his king.

Arthur heard his servant well before he made his entrance – hurried footsteps, banging and clanging followed by mild cursing – who else could it be? Merlin tumbled into the room looking quite dazed. He managed to navigate the short distance between the door and the king's desk with difficulty; narrowly avoided hitting a pillar as he weaved his way across the room with a scissoring gait.

"Sit," the king commanded, a slight smile playing at the corners of his lips. It was like watching a baby foal. Even when they'd gone drinking with Gwaine Merlin hadn't gotten this intoxicated – perhaps this could be fun. Given how frequently his servant was supposed to visit the tavern he should have seen him lose control at least once - but he never had. Merlin wouldn't ever let go or completely relax; his guard was always up – suddenly that seemed a little odd.

Merlin's hand missed the back of the chair; on the second attempt he found the target and lowered himself onto the seat with a flump. The dark-haired man blinked, his gaze darting around the room like a hungry mosquito. Finally his blue, distinctly glazed eyes found the king.

Arthur started to feel a bit uncomfortable watching the young man struggle. Merlin's complexion was pallid, he licked his lips as if he were thirsty and he was looking at his hands as if discovering them for the first time – rotating his fingers, then waving them in the air as if following an imaginary trail. Surely Merlin was meant to behave like this after ingesting the potion? It was one of the side effects wasn't it?

Arthur had seen many knights overindulge (one in particular), they would become uncoordinated and sometimes sick. He desperately wanted to believe that was all that was wrong with Merlin, but his instincts told him there was more to it than that.

"Merlin?"

There was no answer. The king approached his servant and tried again.

"Merlin?" Arthur knelt down until he was at eye level, "Merlin are you alright?"

At first there was no response but then came a soft reply, "No, I don't feel right, it's never done this before," he became distracted again, waving an appendage in the air. "This is all wrong, it can't be happening," his voice was shrill.

Before the blond perpetrator could ask his victim about the strange comments and behaviour, the warlock provided a rather startling piece of information:

"I'm going to be sick!"

Arthur frantically looked around for some vessel that could be used should his servant follow through with that threat. Spying a fruit bowl he vaulted over the bed, tossed the contents on the floor and sprinted back to his friend, shoving the wooden container under the nose of his servant.

Nothing happened, just the sound of rasping breaths and the vibration of apples rolling around the room. The royal was worried now; Merlin never admitted to being unwell, and to top it all he seemed to be having some sort of panic attack.

Merlin grasped the bowl like it was his only possession and he was frightened someone might steal it. The mop of black hair came up, revealing a grey face dotted with perspiration.

"I just need a minute," he threw his head back and let it fall against his shoulders, taking big gasps of air – not alright at all.

The king, a self-proclaimed man of action, was bewildered. He did not know what to do; this was not the effect he had been expecting. Get help? But Gaius would need to know what I've done. No, surely it's not that bad is it? Perhaps I'm not to blame, there could be another cause couldn't there? The guilty man poured a cup of water and was surprised by how his hand trembled.

The blond knight approached his servant and supported Merlin's skull carefully in his palm, bringing him upright. His hair was damp and he radiated heat. Arthur's other hand pressed the goblet to pale lips and encouraged the younger man to drink.

"Come on, just some sips," he urged.

Merlin obliged, then with eyes still firmly closed added, "Anyone would think you care."

"Merlin!" The royal jerked, but he could not keep the relief out of his voice.

The warlock seemed to rally; he came into a sitting position and was able to balance on his own, blinking rapidly as he took in his surroundings.

Something was terribly wrong. Merlin could not concentrate, too distracted by pain. He felt like a stake had been driven into his temple and his stomach churned. He tried desperately to prevent the writhing snakes from breaking free. These ailments were the least of his worries – his magic was going haywire, frantic and fizzing, bubbling under his skin, trying to get out. He could not understand what was causing this reaction – it had never happened before.

"It doesn't make sense," he swallowed, rubbing his thumb and index finger against a clammy forehead, "I was fine - tired maybe," he said with some confusion.

"Something you ate?" offered Arthur. Like truth serum? His conscience screamed.

"Nothing." Having relinquished the empty bowl, Merlin had started scrutinizing his fingers again. He made swirling shapes with his hands, gaze following the movements as if it were a troublesome insect.

Arthur ignored the servant's aerial display. "What? You've eaten nothing?" He questioned in a heated voice.

"Nope!" Merlin seemed oblivious to the blond man's burgeoning rage, too intent on wiggling his own digits.

"You were supposed to have something – it helps a cramp, you idiot!"

"I took a pain killer."

"That's not enough!" Screeched the king.

"There was no time; there is never any time," snapped the sorcerer, "not when you and Gaius always want so much," he added wistfully. The dark-haired man was staring at something over Arthur's shoulder. "Felt nauseous - couldn't eat," he supplied, distracted, and pulled a face.

Suddenly the warlock had a revelation; he turned and looked intently at Arthur. Merlin crouched slightly and cupped his hand to the side of his mouth, "I think someone is trying to kill me!" He whispered, eyes darting from side to side before fixing once again on something behind the king.

Arthur was a little taken aback, "Don't be ridiculous Merlin, who would want to kill you?"

The king's tone was sceptical, but he could not stop himself from following the younger man's glare. He turned towards the corner as if expecting to see an assassin, but of course it was empty. His attention went back to his servant.

"Too many!" was the matter-of-fact reply, "Mainly the same ones who try and get rid of you – I get in the way." Merlin wagged his finger and raised his eyebrows for emphasis.

Arthur froze; he'd heard that phrase before. Merlin had used those exact words when reluctantly explaining how he came by a large burn, central to his chest. He'd been hurt defending his mother, had even killed the perpetrator. The royal thought that was the end of the tale, but this implied there was more to the story. Had his servant sacrificed himself multiple times, more than his many scars suggested? The king's train of thought was interrupted by his servant's triumphant cry.

"Poison!" He shouted, sounding almost pleased that he'd worked out the answer to the problem.

Arthur's mouth went dry. No, it couldn't be could it? It was a truth tonic, that's all - designed to loosen his tongue, make him a little inebriated maybe - certainly not toxic! A terrible realisation began to dawn on the royal. The physician's ward was familiar with all manner of potions and he'd been poisoned before – he'd drunk it to save the life of an arrogant prince he barely knew. Arthur grabbed his hair in frustration; bile bubbled in his throat. He had absolutely no idea what was in that vial. He should have known something was wrong; Merlin had said the water was disgusting when it was supposed to be tasteless. Gaius had even told him that very day that the properties of medicines change over time. Oh what have I done? Merlin answered his question for him.

"I...I think I'm dying!" The pale man rubbed his throat and examined his hand again, then he turned towards the royal looking horror-stricken.

"Don't be such..." the words died in his throat, "What makes you say that?" Arthur croaked nervously. It couldn't be that bad, there must be a mistake. He needed to get Gaius.

"Isn't it obvious?" The servant was incredulous as he frantically waved his arm in front of Arthur, "Look, it's leaving! It's..." Merlin suddenly stilled and began to frown. He slumped into the chair and let out a long sigh. Slowly his head levelled, gaze trained on the royal. "You – you gave me the water-skin," Merlin's eyes were wide – a finger pointed at his king. "You..." his breath caught, "you insisted I drink all of it," his voice shook with disbelief.

Caught red-handed, Arthur could not hide his guilt and fumbled his words; he stretched out his hands, palms open as if trying to calm a wild animal. "I, it's –it's not what it looks like." Arthur's head spun. I didn't think you'd get sick! You weren't meant to find out; it's all going wrong.

The servant looked terrified and seemed to shrink into the seat, "You know?" His breath hitched and all remaining colour left his face.

"I know nothing, Merlin," the royal looked skyward, "that's the point!" He said through gritted teeth as he balled his hands into fists.

It was no justification for what he had done. When he had planned this it all seemed so simple; the reality was anything but. Trust was the linchpin of friendship and he had tossed it aside like a piece of rubbish. Merlin's secret had been a stone in his shoe and rather than dealing with the irritation appropriately he had thrown away his footwear and been left barefoot, dancing on a sea of broken glass.

When Morgana turned it had been a dagger to his heart, when Guinevere chose Lancelot the blade cut savagely as it twisted, and when Agravaine had shown his true colours it was driven deeper until he thought there was no greater pain than being betrayed by those he had loved – but giving was so much worse than receiving. Arthur could hardly bear to look at the expression etched on his friend's face -one he had never wanted to see. The king couldn't have done more damage if he'd unsheathed his sword and plunged it into his servant's flesh. Right now he wanted to take it all back, rewind time, but he could not. Little did he know there was worse to come.

Merlin lurched to the side and crashed to his knees, up-turning the chair and sending the bowl skidding across the floor. He was violently sick; body taut on all fours, convulsing as the retching continued. Eventually the servant rolled onto his back, exhausted.

Arthur stepped towards him cautiously and knelt, placing a hand on the fallen man's shoulder only to have it pulled away as Merlin scuttled backwards, away from the mess and from the king.

"Merlin wait, I'll call Gaius, I'll...," he advanced and Merlin continued to move back, gaze never leaving his sovereign.

"It's not your style Sire; I thought the gallows were a possibility or the pyre, a sword maybe, but poison?" Merlin threw back his head and let out a brittle laugh, "Morgana would be so proud." The warlock threw open his arms, addressing the ceiling, "Are you happy now? Have you had your revenge?"

Merlin seemed unhinged; he did not normally show anger or bitterness, only if he was pushed beyond endurance, so this display chilled Arthur to the bone.

"Merlin, Morgana's not here – for once this has nothing to do with her."

"I know that!" He barked, then his arms and head flopped back down. The fight was all gone, replaced by sadness, "I never thought...I hoped it would not end this way." The pitch of his voice was now barely audible.

"What are you talking about? I'm not going to hurt you, you idiot."

The servant surveyed the monarch, anger long-since dissolved into disillusionment, "You already have."

The words stung. The king pulled at his hair and stamped, "I didn't know this would happen! Damn it, you're my best friend!" He shook his head and gazed at the floor, "I would never do anything like that on purpose – Why would you think such a thing?"

The warlock let out a faint snort, "The things I've done. What I am."

Arthur did not even register the response; he was so riled and desperate to defend himself that he did not hear Merlin and instead ploughed on with his plea, "I only wanted the truth!"

"Truth?" Merlin spat out sullenly. "Really? The truth hurts and you couldn't deal with it!" He shouted, then turned away deflated. "I tell you the truth all the time and you don't want to believe it," he looked up at his king and sighed, resigned. "You see and hear what you want to, not what's really there. That's why I could never tell you," he added quietly, "If you really saw, you would have to choose." The dark head flopped forward, crestfallen.

Arthur wanted Merlin to stay angry; he could deal with that. He could hold his own in a fight, but his friend had fallen silent. It was like Merlin expected this, knew his king could treat him this way. That comprehension, coupled with the enormity of what he'd done, made the royal want to vomit. Things had gotten out of control so quickly – like trying to coax a flame only to have it turn into a raging inferno destroying all in its path until nothing is left but ash.

Nothing made sense anymore. For once the servant had not tried to be evasive and dodge the questions; he had answered truthfully and from the heart but his responses were still riddles to Arthur. However, if the king would only listen, all the answers were already there – and there was some part of him that knew that.

Before the monarch could seek clarification, the thin thread holding Merlin up snapped and he collapsed. His skin was waxy and white, body still – Arthur feared the worst.

Sprinting over, the royal grasped at his servant's neck, relieved when he felt a pulse – it was barely there, weak and thready.

"GUARDS!"

Oak doors were flung open and the men who were permanent fixtures outside the king's chambers rushed in.

"Go and get the physician – NOW!" He ordered, not even turning his head away from the floor and his fallen friend.

The men almost tripped over themselves in their haste to complete the task, such was the fury in the king's tone. The guards were used to being statues and had a similar amount going on between the ears but the royal was confident they would be able to follow his orders to the letter. He heard the sound of retreating footfalls slapping the stone floor and sighed, assured Gaius would soon be on the way.

The king knew the situation was dire. He'd seen plenty of causalities on the battlefield and he instinctively knew when a knight would not make it – there was a certain aura about their body. He'd felt death's putrid fingers on his own skin in the past, but had been lucky enough to elude their grasp. He'd lost many and taken lives himself when necessary - but never like this.

Arthur watched, paralysed, as his servant lay motionless on a dusty stone floor, devoid of any visible injury. The royal was numb; a bitter chill crept up his spine as if he were being encased in ice. This could not be happening. Merlin had the look and feel of one whose life was ebbing away, a hair's-breadth from becoming a corpse - and it was entirely his fault. He could not breathe; his chest was tight. Arthur, King of Camelot, a respected and so-called honourable knight had poisoned his best friend.