I do not own Merlin, all rights belong to the BBC.

This little story is based on an idea I had a long time ago - before I even wrote any Merlin fan fiction. I got inspired to revisit it after reading a piece from the wonderful April29Roses - thank you.

I would like to thank Caldera32, who once again was my beta. She also created the fantastic cover art.

I hope you enjoy this, thoughts and comments are always appreciated.

Chapter 1 If I Could Turn Back Time

Everything looked different in the moonlight; the shadows made things that were safe and familiar seem strange and sinister. It was ridiculous; Arthur was a grown man - a king - he'd not been plagued with such insecurities for years. Yet here he was, wide awake hours from dawn, noting every detail of the ornate bedchamber that had been his for as long as he could remember. He wondered if it would be the last night he'd spend in this room. He tried to banish such thoughts and instead listened to the even breathing of his wife, envying her ability to sleep when his mind refused him the same courtesy.

Tomorrow he would ride for Camlann and he was under no delusions regarding what they would be facing. The odds were against Camelot; Morgana had sorcery and an army of Saxons at her disposal. He may have the bravest and most skilled soldiers in all the five kingdoms but what use was courage, the knight's code, and honour against an enemy that had no morals and would stop at nothing?

Arthur had no choice; he had to ride out and meet the threat head on, could not afford to wait for the witch to descend on his kingdom. He needed to protect those unable to defend themselves. Commoners, families, and farmers were not taught to take arms nor should they be. A king must do everything to save his people.

Merlin was a commoner. He was loyal above and beyond what was expected yet when his servant (a man with no military training) had refused to go with him into battle, Arthur had been shocked and disappointed. Merlin had always been there without question, so what right did a knight have to infer the man was weak after everything they had been through in the past? Arthur needed Merlin more than he wanted to admit, craved his counsel and company, but couldn't bring himself to say it.

He'd lashed out in hurt and fear and wrenched apart a bond that had once been so strong - that he'd thought was unbreakable. How the royal felt that loss now. He desperately wanted to take those words back and would reverse the sands of time if he could. What if he never saw Merlin again? He'd effectively called his closest friend a coward when it wasn't true. He needed to put things right.

Arthur stilled; the hairs on his skin prickled and his throat became dry. He listened intently, holding his breath – there was an intruder. The monarch had been so consumed in his own thoughts he'd not registered the presence of a third party until now. Lying on his left side, facing away from the door and window, he couldn't see and daren't move. Had Morgana sent an assassin? Would she be so underhanded as to try and finish the job before he even reached the battlefield?

Reaching under the pillow, his fingers curled around the hilt of a dagger he always kept there. He held his breath, focusing on the location of the other man, then sprang up, twisting his torso to launch the blade in the direction of the figure. Too late did he recognise the gangly form.

"MERLIN!"

The dagger shot through the air. A flash of silver flew past the wide-eyed servant and imbedded itself in the wood of the wardrobe with a small thud.

Arthur swallowed, studying the vibrating hilt of his weapon, thanking the gods he had impaled the furniture and not his friend.

"You can see me!"

"Of course I can bloody see you. What the hell are you doing standing by my window in the middle of the night?"

"I… I..." The usually talkative man fumbled to find words, his gaze never leaving the king.

"What is so important? What couldn't wait until the morning?" Arthur demanded.

Merlin just stared back, silent.

"Merlin?"

On getting no response, Arthur calmed and became unusually perceptive. "Is this about what I said? About you not being in Camlann? Because -"

"You ride for Camlann tomorrow?"

For a moment the royal just stared, incredulous. "Merlin, we discussed this – you told me you wouldn't come -"

"I'll be there."

The king's mouth fell open, then the corner of his lip quirked. "You will?"

The servant nodded slowly, picking at his cuticles before looking up. "I won't be in time, but I'll be there."

"You won't be riding out with me?"

Merlin shook his head.

"I don't understand."

"There's something I must do first..." Merlin brought his hand to his face.

There was an awkward silence, then the servant spoke with such urgency it made the royal jump.

"Don't go, Arthur. Don't go to Camlann; stay here." Merlin pleaded.

The king's face darkened at the sudden request.

"You know I can't do that." He snapped, running his hand through his hair. "I thought you knew me, Merlin – better than myself sometimes. I can't ask my knights to risk their lives whilst I cower in the castle. The battle maybe unwinnable but I have to try - "

The dark-haired man interrupted, desperate to make the royal understand. "You're wrong; Camelot will win. Morgana will be defeated and the Saxons will retreat."

Arthur hesitated, this was the Merlin he knew - the man with endless optimism. For a moment he'd thought Merlin had been replaced by an imposter; the man standing before him looked the same but his eyes were dead.

The joyous words did not match the flat delivery. The servant's shoulders were slumped and he gave a sad smile. "Please don't go, Arthur."

The royal clenched his fist in exasperation. "You've just told me we'll be victorious."

Merlin nodded vigorously. "Yes, Camelot will succeed… but..." He bit his lip.

"But what? You think I don't know the danger? I've had a price on my head since the day I was born; I had no choice about being a royal - a Pendragon - but I'm proud of the kingdom I've created. What would you have me do, Merlin?" Arthur made wild gestures with his arms. "Shall I hide? Deny who I am just because there are those who would see me dead? I will always fight for what I believe in."

"This is different."

"No. Every time I draw my sword, it could be the last."

"Camelot is nothing without her king."

"That's not true; you forget I don't rule alone and if I fall, Guinevere will be a fair and just queen."

"Yes."

Arthur let out a sigh of relief but Merlin had not finished.

"An honourable and strong queen... but not a happy one."

The king slammed his hand into the mattress. "Damn it, Merlin; I've never been afraid to die!"

"Well you should be!"

It was frightening what a formidable opponent he could be; Arthur had never seen Merlin so worked up. He was shouting now, moisture reflecting off his cheeks.

"He won't be reasoned with; he won't stop, Arthur. Even after the battle is lost, Mordred will come after you – he wants revenge."

"Mordred?"

"Yes Mordred. It was him all along and now he's sided with the witch."

"Merlin," Arthur warned.

"What? You want me to tell you it will be quick and painless? It won't. It will take days. He'll pierce your chainmail on the left side of your abdomen, just beneath your ribs - a fatal wound with an immortal blade. Nothing can be done for an injury like that; there's no way to stem the blood or ease the pain. I won't be able to stop it – nothing will."

"Enough! Merlin, this is not you – you're not thinking straight."

"No, things have never been clearer. Don't you see? I'm trying to warn you!"

"Sit down, Merlin."

"No. Arthur, you have to listen. If you knew something bad was going to happen, wouldn't you try and change it? I never gave up – I will never stop trying to put things right."

The king slowly shook his head.

Merlin dropped his gaze to the floor and his shoulders began to shake.

In pained Arthur to see Merlin like this. He was worried - experienced warriors had been known to lose their nerve before a big conflict, but this was different. This was something else entirely.

"You're not well, Merlin; what you're saying makes no sense. I'll take you to Gaius."

Determined to escort the sick man to the physician, Arthur pushed back the covers, planting his feet on the cold floor. He reached the end of the bed before realising Merlin was gone.

"Merlin?"

The king looked around the bed chamber; there was no sign of the servant.

"Merlin?"

With a thundering heart Arthur pushed back the curtains - nothing. He strode across the room, pulling at the door - it was locked from the inside.

The monarch's hand dropped from the latch as if stung and he slowly backed away. A coil of unease settled in his stomach and he gave an involuntary shiver.

"Arthur?"

He flinched, forcing a smile onto his face before turning towards his wife.

Guinevere squinted, sitting up. "What's the matter; why are you out of bed?"

Glancing around the room again and finding nothing he padded towards his partner, meeting her outstretched arm with his own, then plopped down on the bed, dazed.

Gwen cradled her husband, pulling him back under the covers and into a hug.

"What's wrong?"

Arthur remained silent for a while then finally whispered "Merlin".

The queen sighed. "He knows you did not mean what you said. He'll come around."

"I don't think he will, Guinevere. He was... "

She rubbed his shoulder. "Come, it's late; you need your sleep. Things will seem better in the morning."

Arthur kissed his wife and nodded, even though he did not believe it. He felt comfort from the warmth beside him; slowly, her hold slackened and her breathing evened out. Arthur was in turmoil but it could not prevent exhaustion washing over him. Finally his body let him sleep but his mind continued to race - dreams plagued him with unsettling images.

Sunlight streamed into the room through open curtains. Arthur awoke with a start; it was much later than he would have liked. There was a knock on the door and for a moment he hoped it was Merlin even though he knew it wouldn't be.

A nondescript servant hesitantly entered, leaving a breakfast tray before silently departing – nothing like the person who usually delivered his meals. The king reflected on the events of the previous night, everything about it was surreal and hazy to the extent Arthur began to question if it had really occurred at all. However, the dagger protruding from the wardrobe told him it had not been a dream.

There were noises coming from the courtyard and the king scrambled out of bed to investigate. His breath caught when he saw Gwaine and Merlin preparing to depart. So he really is going through with this?

Merlin was leaving and Arthur was struck with a sudden urge to bang on the glass and yell. He'd not meant what he'd said. What if I never see him again? If he moved quickly, he might catch them before they left. He ran across the room but ground to a halt before even reaching the door. Snippets of the conversation from the previous night played over in his head:

"I'll be there. I won't be in time but I'll be there... If you knew something bad was going to happen wouldn't you try and change it? ... Mordred wants revenge... It will be painful, a fatal wound on the left side of your abdomen, just below your ribs."

Arthur jumped when he felt a hand on his shoulder.

"Guinevere!"

The king embraced his wife, holding her in a firm hug - longer than strictly necessary. They pulled apart.

"Addressing the people in your bed clothes is not befitting of a king." She teased.

"No. I-"

She grasped his hand. "It's a big day, Arthur. Let me help you get ready for it."

Merlin clawed at the floor and took a shuddering breath. It would be a few hours before he had the energy to move. A spell of that magnitude would take time to recover from, even for him. It would be days before the pain subsided and the shakes stopped.

His shirt clung to his back and perspiration trickled down his cheek but he did not care. It was the closest he'd ever been to changing things.

The first time he'd managed to go back he'd been forced to watch - a helpless observer - reliving it all again. He'd seen Mordred stab his king and been powerless to stop it. It had taken a few years to get over that.

The second time was almost as bad. He'd arrived too late, materialising in front of Morgana - but she could not see him and he could not interact with the physical world. The witch was demented, screaming for Arthur to be found and for his death. The warlock would have killed her there and then if he could - it would not have saved his king but perhaps Gwaine would have lived. Seconds before he was driven back to the present, the murderess seemed to sense him.

Although shaken by the encounter, it had given him hope - perhaps there was a way to change things. He'd dedicated all his time to research and experimentation, though he never touched the dark arts no matter how tempting.

On previous occasions the spell had used so much energy that once in the past he could no longer access his magic or influence physical matter. This time he'd had no idea when he'd arrived, only that Arthur was still alive and sleeping. It had been enough just to watch the steady rise and fall of the king's chest. To his surprise, the royal had sensed his presence, seen and spoken to him. Merlin had not even been corporeal – imagine the irony if Arthur's dagger had pierced his heart rather than passing straight through? Not that it mattered, he wouldn't have died, but it would have been difficult to explain. Injuries, hurt, and pain he can experience, but death is too good for him.

The warlock tried not to be bitter. There was relief at finally seeing Arthur again and now he had new words and images to remember. Things were already a little different but it was foolish to think he could have changed the king's mind, to think he could have altered anything significant. He was not wistful; he was weary, old, and desperate. He'd waited centuries; endured wars, famines, and all manner of natural disasters but the Once and Future King had failed to return.

Time travel was difficult, even he did not understand all the complexities. He knew that one could not continue to exist in the past with definite knowledge of the future but what about two versions of the same person? Would they cancel each other out completely and cease to be or would only one survive? What would have happened if he'd seen his past self rather than Arthur?

This was why altering time was forbidden. If he succeeded, there would be a price to pay - but wasn't fifteen hundred years alone penance enough? What more could be taken? He was already stripped bare, a shadow of his former self. Destiny had promised much and not delivered. Was it so wrong to seek to change things after all these years? Had he not always been faithful and true, striven to do the right thing, been patient beyond endurance? His reward for this long service had been to lose his king and all hope - not anymore.

Merlin rolled onto his back, losing his vision. He would dream now, vividly, like being there all over again. That was alright, because when it was over he would just go back and start again. Fine tune the spell, collect the many reagents, and wait. No matter how long it took, he would keep trying until he was successful – Emrys was, after all, the one person who had all the time in the world.

"Merlin? Where have you been?"

The warlock looked at the ashen face of the fallen king. He grasped his friend's hand, pressing it into his cheek.

"It doesn't matter now."

Arthur winced, throwing his head back. "My side."

The servant glanced at the hole in the chainmail. "You're... wait, there's no blood." He heard himself say.

This was new. The scene had never changed before; everything always remained the same - like reading from a script. He wasn't dreaming, the air smelt of the earth, copper, and death. He could feel the breeze on his face, damp seep into his clothes and the prickle of magic under his skin. This was real, but where was his other self? What happened now? Was the outcome the same and only the detail different - what was the point in that?

A sharp grunt brought him back to reality with a jolt - Arthur was hurt.

"You're injured."

"Really, Merlin? I thought it was something I ate." He hissed in pain and clenched his teeth. "Help me out of this armour. I can barely breathe."

Merlin's hands trembled as he undid the buckles and pulled away chainmail. He'd never seen the open wound made by Mordred's sword. It would have caused Arthur too much distress and served no purpose.

Taking a big breath, Merlin tried to prepare for what would greet him; there should be a lot of blood but the blade's incision would be small, belying the damage wrought to the organs below. Tentatively he undid the ties of the doublet. Instead of the king's flesh there was an additional square of metal secured with a strap; it was dented in the center. What? Merlin could see the king's chest heaving against the strap and hastily cut through the restraint to release the iron plate.

Arthur's torso was mottled red and purple. A large haematoma extended from his tenth rib to the crest of his hip but there was no break in the skin. Merlin's fingers ghosted over every inch of the king's flesh, palpating muscle and bone, assessing the damage.

Arthur grunted in pain and sweat formed on his brow.

"Fractured ribs." Merlin managed to say, smiling as moisture built up in the corners of his eyes. "Just fractured ribs and some bruising."

"Is that all? I thought it was serious." Arthur clutched at his side.

"It is, but not fatal... Arthur, you're going to live."

Merlin threw back his head and looked to the sky. Can this be? He let out a hysterical cry and picked up the small square of metal, shaking his head.

"How?"

"I do listen sometimes. Besides, I married a blacksmith's daughter – it has its advantages."

Merlin nodded, relief flooding his features. "Yes, it certainly does... Arthur, do you know what this means? You… we ... the prophecy has been defied!"

The knight grasped the servant's wrist, his breath hitched but the grip tightened. "How did you know, Merlin?" Despite the king's frail appearance his grasp was strong. "Answer me. That's twice you've disturbed my sleep and saved my life. How is that possible?"

The warlock looked at all the confusion and fear that clouded his king's face. It would be hard but Arthur deserved the truth. After all these years Merlin could give him that.

Wanting to tell Arthur and having his mouth cooperate were two different things. The words just got stuck in his throat. Merlin coughed, shaking his head and causing some discomfort and dizziness. He ignored it, determined to do this right.

Before the words fell from his lips a searing pain exploded inside his skull. Instinctively his hands pressed into his temples, trying to stop his head shattering. He dropped to the ground, writhing in agony.

Changing time is forbidden; there is always a price... One can't exist in the past with knowledge of the future… Would two versions of the same person cancel each other out?

"Go on, take me - my life for his, a servant for a king - that's fair." He ground out.

It had taken fifteen hundred years to finally do what destiny had told him to – protect the Once and Future King. He had lived long enough and could let go now, knowing that Arthur lived.

He thought he heard his name being shouted and tried to open his eyes to look on his friend one final time. There was a roaring in his ears but he had to tell the truth before it was too late.

"I have magic, Arthur. I used it to save you. I'm sorry... but you had to live…"

Enveloped in a blinding light, he knew no more.

"Merlin?"

"Am I dead?"

Gaius chuckled, wiping a stray lock of hair from his ward's clammy forehead. "No, my boy, you are very much alive."

"It feels like I should be dead."

"Well, that was some very powerful magic you performed. I'm not surprised you're exhausted. What's the last thing you remember?"

"Sending Aithusa away. Finding Arthur - ARTHUR!" Merlin tried to sit up.

"The king is resting -"

"The wound, his chainmail was pierced - I was too late -"

Gaius grasped Merlin's shoulders. "Calm down. There was no incision, Merlin. Fractured ribs and contusions but the skin was not broken."

"He'll live?"

"Yes. It will take some time to heal but he should make a full recovery."

"Mordred, Morgana?"

"Mordred is dead - at Arthur's hand." Gaius shrugged. "Morgana is out there somewhere but she failed and her army is defeated. The Saxons have deserted and fled for the hills but Leon sent two hundred men after them to make sure."

Merlin flopped back against the pillows. "We did it, Gaius: prevented the prophecy."

"You did it, Merlin. The fate of a kingdom rested on your shoulders and you saved us - we owe you a great debt." The physician rubbed his hand, then paused. "You really don't remember, do you?"

The servant shook his head.

"Arthur wants to talk. You told him something just before you passed out."

"I did?"

The old man nodded.

Merlin paled. "What...what did I say?"

Gaius squeezed his shoulder. "It can wait. The king's been informed that you are in no fit state for questions. Rest now, my boy - you deserve it."

Rest he did. He was so tired, as if he'd lived for centuries rather than just twenty-eight summers. For the first time in months he would sleep deeply and in peace. Ever since he'd heard of Arthur's bane and seen the vision of Mordred killing the king he'd had a constant ache in his heart and been driven to do all in his power to prevent it. Now that pain was gone, the future was not set and anything seemed possible. Maybe the time for keeping secrets was over - the thought of telling Arthur about his gift no longer seemed so daunting. Perhaps Camelot's golden age had truly begun and Albion would exist after all.

TBC

So, What do you think?

My fix it fic - because I still feel bitter about how they ended the series!

AU, Seemingly, quite a few of you are asking for a sequel / second chapter dealing with Arthur's reaction. This originally was only meant to be a one shot but there could be scope for more - after all there is a mad witch out there with some unfinished business.

Now a three part story

Ps April's story is called Blood Moon and is very good.