A/N:

Hope you guys enjoy this one! I had this idea during a blackout and decided to write it down.

I don't own Merlin

CHARACTERS: Merlin, Arthur, Gaius & Knights (someone quite bad too)

RATED: T

GENRE: Hurt/Comfort & Horror...probably a touch gory too

Merlin is acting strangely, and Arthur tries to get to the bottom of it – but a dark force inhabits his loyal friend, killing him slowly for fun.

THE ADVENTURES OF MERLIN

The Devil in the Flesh

Arthur couldn't pinpoint the exact moment that the change occurred, but there had been a few instances in which the King could see that there was something terribly wrong with Merlin.

The first, were the dark smudges that sat beneath dull eyes, stark against the pallor of his skin – like it had been some time since the boy had slept. Secondly, was the change to his body; Usually on the unhealthy side of slim anyway, Arthur began to notice how much more his cheeks had hollowed out and the way his hip bones were visible through the material of his breeches. Lastly and possibly the most concerning, were the deep, bloody scratches down his arms that Arthur had noticed several days before, when the young man fainted from exhaustion during a training session. He had been ordered to take a week off at least and eat something, but Merlin kept turning up every morning, dutifully serving his master and King.

Arthur was currently perched atop his desk, watching his friend move slowly around his chambers, picking up scattered clothes for washing.
'You should take the rest of the day off,' the King said casually, noticing the stiffness in the boy's body.
'If I wanted your opinion, I would have asked for it.' Merlin snapped in reply, shocking the young man to his feet.
'Merlin...are you alright?'
The youth sighed angrily, but continued his chores. 'None of your damn business sire.'
Arthur frowned. This was something entirely different and somewhat concerning. He approached the young man slowly, hand out to offer comfort but from his crouch on the floor, Merlin jerked his head around, fixing the King with a glare so dark it made Arthur's skin crawl.
'Touch me and I will pull your innards out with my teeth and send them to Guinevere along with your head. Now fuck off, can't you see I'm busy?'

Arthur flinched, concern for his friend slowly being replaced by an all consuming rage. With no effort at all, he pulled the waif to his feet by the lapel of his jacket and slammed him against the wall.
'What the hell has gotten into you?' Arthur demanded angrily.
The youth grinned coldly. 'Funny you should ask,' he replied. 'You know, speaking of Gwenny, do you know she kissed me once? Right here?' Merlin puckered his lips and his grin widened. 'I could have fucked her, you know? That beautiful tawny skin –so soft and warm beneath my fingers as I pounded into her…those supple breasts in my face. I still may. I could force myself onto her – she wouldn't like it much, but I always did prefer a struggle, what do you think?'
During his speech, Arthur could feel his blood boil, hatred bubbling within his gut. He wanted to grab his sword and run the traitorous bastard through right now, but he settled for slamming the youth's head against the stone instead. Gore splattered the wall behind him as the skin split, but instead of losing consciousness as Arthur expected, Merlin giggled.
Not the way a child giggles when they see something wondrous for the first time, but a maniacal giggle that sent shivers of fear down his spine. Merlin closed his eyes and leaned back, still chuckling darkly. When he opened them again, Arthur's breath caught in his throat. Black shrouded the entirety of his irises, so complete and utterly evil that the King couldn't help but think his friend was no more.
'No…he's still here,' not-Merlin assured as though he read his mind. 'Huddled in a corner of his mind, begging me like a child to release him, but do you know what?' He reached out and gripped Arthur by the throat. 'I have been a prisoner for…such a long time, and I am bored. I want to have some fun. You wanna see a trick?' He asked, grin widening as Arthur struggled to breathe. 'See…you can't hurt me – I can't hurt me, the only one who will feel the pain, is dear Merlin.'

Arthur tried to open his mouth to respond, but not-Merlin squeezed harder, his obsidian eyes cold and cruel.

'Seriously Arthur, I can guarantee that you will absolutely love this!'

His eyes flashed a hypnotic crimson and he winked, his wicked smile broadening his lips as a cracking sound filled the King's chambers.

Arthur paled and looked down to see blood staining Merlin's blue tunic.

'That isn't even the best part...bye for now!'

Merlin took a great gasping breath and his hold upon the King loosened. The guttural scream that passed his lips just about tore Arthur's heart into pieces.

He crumpled at the knees, sinking boneless to the floor – lids fluttering.

The King caught him gently under the arms and slowed his descent. 'Merlin?' He asked, unsure.

The boy nodded slowly and peered up at Arthur, cobalt eyes glistening with tears.

'Please help me...' he whimpered pathetically, breathing laboured. 'It won't stop hurting me...'

The King rested his palm on the youth's pale neck. 'How long have you been like this? When did it start?' He asked gently.

Merlin choked back a sob and leaned forward, resting his brow on Arthur's shoulder. 'A little more than a month ago...' he replied shakily.

The King frowned. 'Why did you not tell me?'

'It wouldn't let me...It took my will. Arthur – what it said about Gwen, you have to believe me, I-'

'Shh, Merlin – I know.'

'You have to kill me, Arthur – I can't suffer at its hands anymore...'

Arthur allowed the first tears to fall as he stroked the blood matted hair at the nape of Merlin's neck.

'I won't...not unless we run out of options,' he whispered softly.

'Then you have to restrain me – and get it the hell out...you have to do it now Arthur, I'm fighting as hard as I can, but it's clawing its way back!'

The King didn't hesitate – he scooped the youth up and rushed over to his bed, settling him gently in the middle and straddling his hips, pushing down on his wrists.

'Use whatever force necessary.'

He gave his friend a short nod and called out to the guards.

As soon as they entered, Merlin began to struggle violently. Arthur strained to keep him pinned, his only advantage was that Merlin was severely malnourished.

'Get your fucking hands OFF me, mortal!' Not-Merlin growled, eyes flashing. The King backhanded him across the face and turned to the guards.

'Fetch Gaius and my most trusted knights immediately. Tell them I required plenty of sturdy rope and the strongest chains we possess. Hurry!'

The guards bowed, eyeing the thrashing boy warily before racing from the room.

'UNHAND ME!' The thing bellowed in a voice that most definitely did not belong to Merlin. Arthur shuddered and nearly fled as pure, unadulterated fear chilled his blood.

'Shut your filthy mouth, demon!' The king roared, hitting him again. It smiled, bloodstained teeth glinting in the light.

'Close, but not exactly,' he hissed. 'Now get off me, before I tear this meatsuit to shreds.'

'Shut...the fuck up,' Arthur growled, his nails piercing the flesh of Merlin's wrists.

It tutted. 'Do you kiss your mother with that mouth? Oh, wait...your mother's dead isn't she? Such a shame too - I just bet she would have been so hot and wet, bouncing up and down on my hips like the filthy whore she wa-'

Before he even realised what he was doing, his fist pounded into the smirking face – over and over, feeling bones break and hot blood on his knuckles.

'That's right, Once and Future King – you keep hitting Merlin like that - but he won't be much use to me anymore and when I leave, I'll make sure there ain't much left to salvage,' It hissed, spitting a glob of blood to the side. As Merlin began to cackle once more, the door of his chambers burst open revealing his knights and a very flustered Physician, carrying the items he requested.

'What in God's-'

'DO NOT SPEAK HIS NAME!' It cried, emitting a gurgling sound from Merlin's throat.

'Who asked you!' Arthur spat, turning to the knights – who stared, in open-mouthed shock at the scene before them. 'Don't just stand there, I need HELP!'

Gwaine was the first to rush forward, followed closely by Percival – who held the chain's in his meaty arms.

Merlin hissed. 'Two's company, but three's a CROWD!'

The young knights flinched at the state Merlin was in, writhing and bucking beneath his King – bloodied teeth gnashing.

'We have to make it safe for Gaius to approach,' Arthur explained, punching Merlin again. 'Something has control of him, and if we can't get rid of it, we will have to kill Merlin...so I suggest you start tying him down!'

The thing in Merlin laughed. 'Bit sensitive this one,' he said, directing his words to Gwaine and jerking his head towards the man on top of him. 'Offer to fuck his wife and he damn near brains me! He should feel special that he has the heart of the fairest in the land!'

Gwaine's eyes widened and he saw the muscle in Arthur's clenched jaw jump as he restrained himself. Merlin pouted. 'Oh come now Arthur! I was beginning to enjoy myself!'

Percival unwound the chains in his arms and nodded to Gwaine and Arthur in turn.

'Leon, I need you at the other side of the bed,' Percival instructed as Gwaine joined Arthur, taking one side each as he continued to trash. Gaius stood at the threshold, his face ashen.

'LET ME GO!'

Leon caught the chain easily and pulled it tight, careful to avoid Merlin's damaged ribs while keeping his arms pinned. He slid his end of the chain under the bed, and Percival followed suit.

Within minutes, it was securely bound, tight around Merlin's slim frame. This was when Gaius finally stepped into the room.

Merlin's black eyes narrowed. 'You,' he hissed. 'You should leave right now old man...I told you I would not be as pleasant when we met next.'

Arthur, with his hands on his hips, met the Physicians gaze. 'What is he talking about – have you dealt with this thing before?' He asked.

'Indeed I have, sire...several times. Each of them did not end well, I'm afraid...'

Merlin grinned. 'Would you like to tell them or shall I?' he asked.

'God above, you are chatty,' Gaius snapped, opening his medicine bag and taking out a small vial of clear water.

'DO NOT SAY HIS NAME!'

'Shut up you wind bag,'

It growled, jerking beneath the chains.

'We are the ones who dwell within,' Merlin began, his voice harsh and deep.

Gaius rolled his eyes. 'Oh here we go...'

'I am the one who dwelt within CAIN!'

'I have heard this!'

'I am the one who dwelt within NERO!

Gaius reached back into his bag with an exasperated sigh and turned to Arthur, who was gripping the edge of the bed with white knuckles. 'Don't mind him, sire – he has a flair for the dramatic, as you have probably heard.'

With a triumphant cry, a revealed an old wooden crucifix.

'I once dwelt within JUDAS!'

'Do hurry up, I don't have all day,' Gaius muttered in a bored tone, as he unstoppered the vial.

'I was with Legion. I am Belial'

Arthur shuddered as Merlin's face contorted into a gruesome mask, his eyes flashing black and red.

'And I am Lucifer, the devil in the flesh.'

The King and knights took a step back in fear, but with a little book, his water and his crucifix – Gaius stepped bravely forward.

'I have exorcised you before, Satan – I can do it again,' Gaius warned, gripping his jaw in his hand. 'And I deal with the stubborn mule every time he gets ill and refuses to take his medicines, so cleansing you out shouldn't be an issue,'

The devil screamed as the water trickled down his throat. 'THEY ALL DIED WHEN I LEFT! What makes this whelp so different?'

Gaius bent down to his ear a smile upon his lips. 'He must have hidden it well,' he murmured, pressing the cross to his brow.

The flesh sizzled and smoked as Merlin's body thrashed. Gaius turned towards Arthur and gave him a smile.

'Could you just reach up and push in the canopy of your bed? It is on a hidden swivel – once you have done that, I will be ready,' he instructed.

A very confused Arthur did as he was told and his eyes widened as the panel flipped, revealing an intricately pentagram, surrounded by runes.

Merlin's eyes narrowed. 'You crafty old bastard,' he spat.

'Watch your mouth young man, or I will wash it out with holy water,'

Gaius opened his book and flicked through the pages.

'Goody, a bedtime story,' It said sarcastically.

'Exorcizamus te, omnis immundus spiritus,' Gaius began, ignoring the cry of pain that came from Merlin's lips.

'Omnis satanica potestas, omnis incursio infernalis adversarii, omnis legio, et secta diabolica,'

The boy began to convulse and shudder – grunts and screams bringing tears to Arthur's eyes.

'Ergo Draco maledicte et section. Ergo Draco maledicte et legio secta diabolica,'

The chains began to crack as Merlin thrashed in pain, his cries hysterical.

'Ut Ecclésiam tuam secúra tibi fácias servire libertáte, te rogámus, Audi nos!'

Merlin arched upwards and the chains gave way. As he screamed, a black cloud was expelled from his mouth and sucked into the chalk drawn pentagram. The windows shattered showering the knights with glass – and as quickly as it began, the maelstrom ceased.

The room was quiet save for the heavy breathing of the knights.

Merlin was still – his eyes closed and lips parted and for a moment, Arthur thought he was dead. He approached slowly, and sat on the edge of the bed, still wary.

'Merlin?' He called softly, resting a hand in his ruffled hair. 'You need to wake up.'

His brow furrowed and a low moan escaped as he peeled his lids apart.

'Ar-tur...I'm s-sorry...' he gasped, blinking rapidly.

'What for you moron? I'm the one who hit you,'

As he soothed the youth, Gaius set to work.

Setting Merlin's ribs was quite a task, but not far into the exercise, the boy lost consciousness. The Physician bound his chest tightly and assured the King that he would heal.

As soon as the wound on his head was stitched, the Knights went to pick Merlin up, ready to carry him to his room, but the King stopped him.

'He will stay here until he has recovered enough to move,'

No one argued.

One by one the Knights left, but Gaius was hesitant. He watched from the door as Arthur pulled his thick quilt up to the warlock's chin and smiled.

He needn't be worried.

Merlin would be safe under the watchful eye of his friend.

Well, please tell me how I did! I had so much fun writing Merlin-as-Lucifer, and I do hope that nobody is too horrified – I mean, that WAS pretty whumpy. Next chapter goes to my mum! Please also note that 'I once dwelt in...' part, was part of the script of 'Exorcism of Emily Rose' which I also don't own, along with the exorcism that is used the most in Supernatural.