Past Faults and Future Perils

Chapter 1: The Spell of Exchange

(Future)

The world swung wildly in Merlin's vision, light and dark, green and brown and blue, and he clutched the earth beneath him to keep from falling off into the trees. Nausea sloshed through him and he bit back a moan that would probably be mocked more than pitied, the company he was in.

What happened to him? Had he fallen off his horse? Hit his head on an unnoticed tree branch? There wasn't any sharper pain he could locate amidst the aching that throbbed through his body.

"There he is. Over there – on the ground."

A familiar voice, carrying notes of unruffled calm and confident control. Sir Leon - not worried, or panicked because of imminent threat…

He relaxed a bit and the unpredictable unsteadiness of his senses relaxed a bit, too, anticipating the realization of accident, not danger. Rustling sounds approached him, one set of boots thundering on the ground, and he winced away involuntarily before it re-occurred to him, friends.

"Merlin?" Percival's voice, quiet and calm – Percival's hands, then, over his shoulder at the base of his neck to keep his head from dropping off onto the ground behind him.

He blinked, and the first thing he saw clearly was the thick brown-gray beard that covered Percival's chin.

Twisting violently away, he vomited into a low convenient bush next to him, his entire body convulsing helplessly again and again.

Percival didn't have a beard. Four seconds ago, when he'd tipped his head back to laugh at some subtle joke Sir Leon had made… Leon's jokes were always subtle…

"Is he okay?"

"Hells, Gwaine – what do you think?"

Wait. Just… Gwaine was there? How on earth was Gwaine there – he'd been leagues away only moments before… But that was his voice.

How hard did I hit my head? How long have I been…

"I think… there's no way we were ever that young, doing the stuff we did back then. We were… just boys. Look at him."

"He was just a boy. Arthur! He's over here."

Arthur. Okay, that was good. Keeping his head down and his eyes screwed shut, Merlin shuffled himself away from his vomit. The king could mock and tease and Merlin wouldn't even mind – much – as long as he anchored some of this disorientation. What happened? What the hell had happened that… Percival had a beard? With gray in it?

Had to be magic. But no one was panicking-screaming-fighting… They were still in the forest, he could deduce that much. And Percival, and Leon… and Gwaine. Somehow.

And Arthur.

"Merlin?" Noises of another pair of footsteps approaching, a rustle of cloth, the touch of another hand. "It's all right. You're safe – you're among friends…"

It wasn't all right. Arthur's voice rumbled soft and low through his ears, soothing and comforting, and it was… his voice, but never his words, his manner of speaking. He never took this tone with Merlin unless someone was dying – and even then, the motions that accompanied the words weren't gentle and careful, but angry and edgy.

Merlin moved to face him, falling back to one wobbly elbow, feeling one of the others move in behind his shoulders.

Arthur had a beard, too. And wrinkles beside his eyes when he smiled. Merlin couldn't look away from the direct intimacy of his gaze, though terror heightened. He was panting and not getting any air. Arthur spoke again in the same dreadfully sympathetic way.

"There was a spell, Merlin, and magic - but you're all right, I promise. You're just… ten years into the future."

Ten years. Into the future.

He stared at Arthur, seeing the truth of the statement, time blurring familiarity slightly. The king had a scar on his face like his father's – no, not like his father's, not one line down his forehead into his eyebrow, but a curve that didn't touch his brow, and another on his cheekbone, circular like the scar of a childhood disease, but irregular. A burn, maybe, and years old.

Merlin's hand trembled as he lifted it, and he couldn't make it stop and he couldn't not touch those marks, evidence of wounds that must have been bloody and of course agonizing and that one might have threatened the king's vision in that eye and if he'd used magic to try to heal it at the time or smooth the scar over and it still looked like that, then it must have been-

Arthur allowed it, bending a little closer into his touch and closing his eyes. "I'm here, Merlin," he said, a bit hoarsely. "I'm alive. For ten more years – focus on that, please. And you're going to be fine."

"Ten years," Merlin rasped. His throat burned from throwing up – and he had to swallow the urge to do it again. "Ten years – how do you know?"

Arthur smiled again, but this time a strange sadness lurked behind the blue of his eyes. "Because I remember when this happened before."

…..*….. …..*….. …..*….. …..*….. …..*…..

(Past)

The spell roared to life around him without warning, and it was a hundred times worse than the traveling spell he sometimes utilized when Arthur wasn't present to stop him with that look he almost always obeyed even when he didn't listen to his king's orders.

It wasn't as bad as he remembered, though. Maybe because – although his timing was off and it took him by surprise – it was the opposite of unexpected.

Still highly unpleasant physically – magic squeezed and reshaped him like dough, punching the breath from his lungs and relocating the bile in his stomach to the back of his throat.

I didn't get to say goodbye - I meant to say goodbye. I meant to say…

And then came the fire.

He had no air to scream, but when the spell ebbed, leaving his limbs weak and trembling, it left his throat raw like he'd been screaming for an hour. 'Cause he knew what that felt like, too.

Coughing and wishing he could manage a water-summoning spell, he blinked black spots from his eyes and dug his fingers into the surface his body was sprawled haphazardly on – the dirt of the ground, soft but not wet and finely webbed with roots. Boughs of green-black leaves tossed above him, scattering the blue of the sky and lifting the hairs of his neck and forearms with the chill of autumn and the receding power of the spell. Same time of year – almost to the day, though his timing was off – but the weather was different. That was almost amusing.

He knew where he was – damn the Valley. Damn the Fallen Kings, too, while he was at it…

It wasn't a spell to move him in space, but in time, and he remembered. Ten years ago they'd been riding back to Camelot from Gedref, searching rather desultorily for Morgana after retaking the citadel from her Southrons – because dead wasn't dead without a body – and that search had felt completely different than the one they'd conducted after Morgause's spell and the poison she'd sworn to counteract in her sister. They'd gone the route through the Valley of the Fallen Kings, against his sourly-spoken advice, and then softer pleading.

Arthur never used to listen to him.

Merlin coughed again and spat out a gobbet of thick spittle, trembling as he made his arms push him up, pulling in his legs so he could tumble back down to a position more nearly sitting, though one elbow remained stubbornly stuck in the earth.

Arthur had to be close. And Merlin found he was more nervous to meet him again than he had been in years.

"Merlin!"

The call of his name from the distance of a stone's throw alerted him to the fact that it was being repeated from further away, the word stolen by the wind and hidden in the tossing rasp of leaves.

It was time. It was starting all over again.

He wished he knew what to expect, but Arthur was always stubbornly vague about recounting this experience from their end of the decade, and the others… didn't know everything, but deferred to Arthur's unspoken wish to leave this bit of the past in the past.

It was a rough go of it, Arthur would admit reluctantly, and Merlin would regret the shadow of guilt, even though he was sure it was largely unfounded. We hounded you the better part of the week, and it was… it was…

That's all right, he'd say hastily, whether he'd brought it up or whether Arthur had worked himself around to broaching the subject. Never mind. You don't have to tell me…

"Here!" he called out hoarsely, lifting his free hand to flap about as a signal to whoever might notice. Only Percival and Leon on this trip, because Elyan had been with Gwen, and Gwaine had been sent… north, hadn't it been? Or southeast to Caerleon… he couldn't at that moment remember.

"Merlin, you idiot! How could you-"

The sound of his king's voice was like a whip-crack for his attention. Arthur's voice had changed over the years – that was unanticipated – he was used to it being deeper and slower, somehow. Confidence that wasn't arrogance, and Merlin had absorbed that without even realizing the change.

For the moment, ironically enough, time seemed to stand still.

Oh, he'd forgotten how young Arthur had looked. Especially without the beard, without those fine lines at the corners of eyes and mouth that made themselves visible too slowly to be consciously noted… without the scars.

Merlin's mouth lifted into a smile all on its own, and tears pricked the edges of his vision.

You have so much ahead of you. Ten years for sure – and haven't we laughed. That always made up for the times when we wept…

The moment couldn't last. Arthur's expression, staring wide-eyed with astonishment at Merlin – I bet you didn't think I could grow a beard, did you, my lord? Well, I meant to shave before this happened, to lessen the shock, but I miscalculated the time – narrowed to realization-

And closed entirely on suspicion.

"Who the hell are you?" Arthur demanded.

"Have I really changed that much?" Merlin wondered, gathering his feet and planting one hand to push himself upright. Balance didn't cooperate, and he flailed for a moment with his free hand for something to hold on to, to pull himself up, but nothing connected to help him, and he only managed to wobble onto one knee. "It's me, Arthur, I'm just-"

Abruptly Arthur shifted into violent motion, and Merlin recognize the hiss of edged steel freed from the sheath at the king's belt before he recognized the movement. It had been years since Arthur had drawn on him, even in jest. Now, deadly earnest glared down at him along the sharp line of the sword that people were beginning to call by its own name, in his time. Ten years into the future.

"Do not move," Arthur ordered, settling his stance deliberately in preparation to use the weapon, not simply to establish his authority before discourse. "State your name and your business in this place, so close to Camelot, and not a single word else."

Merlin felt like he might vomit again, the spell turning his stomach worse than one of Aithusa's mid-air maneuvers, and the threat of such an embarrassment made him short-tempered. He smacked the tip of the sword away with the backs of his knuckles against the flat, rolling the other direction to gain his feet.

"Hells, Arthur, can't you see it's me?" His joints wobbled irritatingly, and he stumbled two steps sideways before regaining balance against the rough bark of one of the great trees that shielded and sheltered them. "It's Merlin, your s-"

Movement followed him and he turned his head fractionally to realize Arthur had not relaxed his position. Arm straight, wrist locked, tip finding a home between Merlin's ribs too firmly for comfort.

He turned the sound of the word that came naturally to his lips into something more appealing than sorcerer. "Servant?"

"That's a lie," Arthur said coldly. He wasn't looking at Merlin's face, but glancing all around as if searching for something or someone, and when his gaze returned to check Merlin, it marked his hands-arms-shoulders as if preparing to counter an attack. "How do you know that name?"

Other shouts interrupted Merlin's scattered focus, further fragmenting it from hells-I'm-gonna-be-sick and what-the-hell-is-wrong-with-Arthur. The other knights of the patrol were returning from various points, calling to each other and tramping through underbrush, and swords were out… and it had been a long time since he'd been skittish about the performance of magic – even someone else's – around Arthur's crimson-clad men.

"Because it's me," he said, exaggerating patience. "Something happened, just now, right? You said there was a blinding flash of light, and everyone reacted at once and it was a bit chaotic and then my horse was riderless? It's all right, I'm right here, Arthur, you don't have to search for me any-"

"I said?"

Through the velvet tunic and the linen shirt, the point of Arthur's sword dug deep enough to taste blood, and caught Merlin's breath in his throat. Instinctively he flinched back from the contact, but his back was to the tree and Arthur pinned him in place with that bright spot of pain and another baleful glare.

"Stop talking," he growled. "I will consider disobedience treason and dispense with your trial."

What? Incredulous – wounded – Merlin opened his mouth to object.

Something that was all Uther – cold dispassion, an inclination to be done with complication by choosing execution – swept over his young king, and Merlin froze again, abruptly uncertain. And unfamiliar.

"As you value your life," Arthur added stonily, "you will never refer to me so familiarly again."

Oh, for heaven's sake. The magic from the spell was draining energy and strength as it receded, and his pulse was whirling round his head with every beat and Arthur was being obtusely imperious.

He couldn't remember that it had ever been this bad between them.

Fine. You're the king. Merlin scowled to himself, clamping his lips shut and letting himself slide down the tree to a more comfortable – more stable – crouching position, knees to his chest to keep every part of him where it belonged. The tip of the blade followed him, prodding sharply but not penetrating further.

The knights were coming. Leon and Percival would recognize him, surely…

"You've found him, then, sire?" Leon called. "Did he say what happened? We thought we saw-"

Merlin watched Arthur's right-hand knight realize he was different. Yes, the beard and also the clothing… Leon stopped midsentence and mid-step.

One of the others – Sir Brendan, was it? at least thirty pounds lighter at this point in his life than he'd been when Merlin left Camelot that morning – picked up the thought. "Evidence of sorcery, sire, as if-"

"Who is this?" Leon interrupted Brendan to ask Arthur.

"He won't say."

"I'm Merlin," Merlin said crossly, even though the point of the sword menaced him inches from his face. He didn't think he was in danger of being prodded with it again, though – a sharp shallow jab to the ribs was one thing, but threatening eyes and ears and neck-veins something else entirely. Something beyond Arthur, even in this mood.

He hoped.

Leon stared at him blankly, then shifted to focus on Arthur for his reaction. In that single second the knight allied himself and his opinion firmly with his king, as if he believed Merlin was a stranger or an enemy. He leaned closer to say in a low, cautious voice, "It's an absurd lie, if it is one…"

"Perhaps he's mad," Arthur returned grimly. "Or maybe he's betting we won't risk hurting him. He knew Merlin's name, and described what we just saw…"

"If Merlin was captured somehow by his fellows, any threat to this man might result in risk of the same happening to Merlin," Leon observed.

Merlin snorted. Stupid. Anything done to him, was done to Merlin, if you wanted to be precise. Just not their young-servant Merlin… for a moment he remembered how it had felt to wake in this place, ten years from now and ten years ago, to find Arthur and everyone else aged a decade, and all he had to do was face Morgana…

"Why would they take Merlin from us at all?" Arthur muttered savagely, turning away.

At least the king let his sword drop to his side, but Merlin realized that might have been due to the fact that he was surrounded. The others had arrived without his conscious notice; he hadn't considered a threat from Camelot's knights in so long he was unbalanced. Percival was one of them – but instead of the little-boy look of wonderment he often wore when faced with the impossible or unexpected of magic, the big knight's face was like granite as he studied Merlin.

Hells, not him too.

"…No other sign of him," Leon murmured, watching Merlin because Arthur's back was to him. "That blinding light was clearly magic, do you suppose it could've-"

Merlin was used to being Arthur's source of information on magic, and as it was the only area in which he clearly excelled over his king and best friend, he often adopted a tone with a hint of superiority, especially when Arthur was being stubborn about it.

"It was a spell of exchange, more or less," he said aloud, digging his elbows into the rough striations of the tree trunk and heels into the ground to struggle to his feet again. Maybe this time upright would cooperate with him. "Combining elements of teleportation and telekinesis and probably the time element is only possible here-"

They stared at him, Arthur's eyes gray-stormy over his shoulder and beneath a furrowed brow, his lips pinched together.

"It's done now, and he's gone," Merlin added, attempting to reassure, deciding to refer to his younger self as he rather than me. He took a confidential step closer to his friend. "But it can be reversed to bring him back, in a-"

"How do you know that," Arthur said softly, enunciating each word carefully.

Merlin made a noise of impatience. "I've been trying to explain just that, you-" The word came out of his memory, prompted by the sight of Arthur so young and irritating- "You clotpole!"

Arthur breathed once, in and out, and Merlin had one second to begin to relax, before the king gestured – fury and violence-

And pain exploded through the left side of his face as Arthur hit him hard, knocking his head back and his feet out from under him again, so suddenly and vehemently he bashed his skull against a root or rock behind him on the ground when he tumbled full-length.

Arthur towered over him, menacing him with the sword again, the tip pushing into the hollow of his throat. Sunbursts of bright pain made him a dark silhouette against the rest of the daylight-dappled forest.

"You are dressed as a nobleman," the king said. "But if you will not tell us your name or where you're from, we will deal with you as an untitled enemy accused of involvement with magic. If you continue to refuse to explain these circumstances to convince us of your innocence, we will conclude that you are guilty. And, having no information of value to us in recovering our fr- our missing companion, we will leave you here as food for scavengers."

And he meant it. Merlin couldn't see his face clearly, but he sounded serious as death.

Merlin's head was pounding again, making concentration difficult, and his hands were up in surrender in spite of himself. Rare were the occasions when Arthur retreated beyond all of them into his responsibility to rule and to decide, but Merlin recognized them and respected them far more than he used to. And he had learned, over the years, when to hold his tongue. When Arthur wasn't listening.

This wasn't exactly his Arthur anyway – if he wouldn't listen, Merlin would have to figure out a way to fix this without his friend's involvement.

"Brendan, you have the command," Arthur was saying to the knight. "Bring this man to the cells."

"We're going to keep looking?" Leon asked, lowering his voice as if he was trying to keep the conversation private from Merlin. Though he glanced down at him, Merlin couldn't read his expression around the headache making his eyeballs swell and swim.

Arthur was already turning away, as the tramping feet of the others intruded, surrounding Merlin.

"I won't give up on him this time."

The raw emotion, nearly smothered – nearly – jolted Merlin out of his irritation. What did that mean?

He lifted his head – needed an elbow down on the ground to keep it up – ignored the shuffling of the knights who had custody of him. He'd forgotten them entirely, from ten years ago when he'd disappeared from this patrol and hadn't returned til now, ten years later for him.

The king strode away, slashing at underbrush with his sword in contained fury, head up and turning in a way that spoke, even from behind, of a gaze searching. Searching, and not finding, and maybe growing more desperate for that failure…

Searching for Merlin. For his younger self, for the hapless manservant. Before they became the friends they were now…

He stared at the king's back, retreating, and remembered that it would have been a little over four months since the days his younger self had been lost in this very Valley, prey to another of Morgana's plots. She'd since discovered that he'd used an aging spell that day – perhaps where she got the idea of switching Merlin so she could bring his younger self to the future to face, and kill. Ten years behind her in experience and skill, when he'd still been untaught and unpracticed…

Merlin snorted softly to himself. He could have warned her against it. Could have told her exactly what would happen – he remembered it – because the very fact that he'd been at Arthur's side for the last ten years meant her plan wouldn't work. Couldn't work. His younger self had to live to return to this time because that's what had already happened.

But then, it wasn't just Arthur being stubborn about listening to Merlin, even if he didn't believe it was him, or reactively spooked about magic taking him by surprise. It meant, even this long ago, Arthur was genuinely worried for his wellbeing, and willing to inconvenience himself and others for the sake of his servant.

And Merlin was used to backwards, inside-out compliments, when it came to Arthur. If he cooperated now, he was sure he'd get another chance to talk to his king, later when he'd calmed a bit.

And in Camelot, there was Gaius.

Merlin almost lost his balance trying to scramble to his feet, avoiding the hands and sword-points of the knights who were trying to prompt him to get up. Camelot was Camelot, and he'd been under arrest before. He'd been to the cells before, too.

Let's go, then, what are we waiting for?

He knew better than to sound eager, but he let them bind his hands and prod him to start walking with minimal resistance. Though it made his heart ache to hear his friends still calling his name, searching further through the woods for him, as he was led away.

…..*….. …..*….. …..*….. …..*….. …..*…..

(Future)

Merlin's head wobbled on his neck. The world kept shifting to the left after he blinked, and he wished it would just stop. All of it. He remembered the helplessness and despair of knowing the future, of trying to stop it, or change it – Mordred, Morgana – use what you've seen for good… and it was impossible.

You have the power… you have the power… you have the power… so then it was his fault when nothing changed, wasn't it? And the worst happened, every time. He wasn't going to be able to prevent Arthur being wounded, when he got those scars, but… He was going to try anyway, wasn't he. And fail…

"Breathe, Merlin," the king advised, sounding sympathetically amused.

If he squeezed his eyes shut tight, he could almost imagine it was his Arthur, speaking. Except for what he said, and the way he said it.

"We might not have much time… Just breathe, and focus on that, right now, and just listen, all right? Morgana set a trap for you, a spell that brought you ten years into the future, while returning your older self to the past."

He sounded so calm it was unnerving.

Merlin shivered and breathed as he was told without opening his eyes. "A spell of transfer?"

"Exchange," Arthur's quiet, compassionate voice said. "We didn't expect it would happen til next week, so maybe we triggered the trap early somehow, but she might still have a way of telling that the spell's done what it was meant to, which means-"

"She's coming," Merlin said, feeling hollow like a scooped-out gourd. "I – I – are you sure about…" Yes, of course it was Morgana, of course they were sure about her, Merlin was sure about her, of course she would attack him if she found out…

Maybe it was all a vivid, crazy dream.

"Yeah. So when you're ready, we should get back to Camelot as soon as possible. There are other magic-users there, people who can help protect you until-"

He opened his eyes and moisture trickled over his cheekbones. "Other magic-users?"

Arthur's smile quirked, but there was still something deep in the blue of his eyes that grieved. "Yes, Merlin. Magic in Camelot. If you don't believe me, get up off your rump and come see for yourself."

"Other," he repeated, stupidly faint because he was fainting, he was falling, he wasn't breathing. "Magic. Users. You mean, you…"

"I know about your magic," Arthur said, his voice soft behind the beard and the scars. "Merlin, please breathe. Yes, I know – I've known for a very long time, now, and it's all right. You don't have to be afraid."

"Mm," Merlin said, because he couldn't manage more than that. "Mor- but, Morgana…"

"She's afraid of you, mate – and I must say, she's got reason to be, from what we've seen." Gwaine grinned, reaching a hand. Silver strands glinted amidst his dark curls. "Ready?"

Not even close.

Because Arthur… Arthur knew… he knew… What did he know? How much did he know? I haven't told him yet, I haven't told him anything – I can't tell him anything because magic killed his father, I killed his father so I can't ever tell him…

They took Merlin's hands and pulled him to his feet. He wavered, feeling overwhelmingly-

"How do you feel?" Arthur said, disorientingly concerned. "Are you all right?"

"Of course," Merlin said, trying to be cheerful. "I'm fine."

And bent double as he vomited violently onto the ground between them. He was quite sure that some spattered onto the king's boots, but Arthur shifted his weight closer, bracing Merlin with a hand on his shoulder. Merlin didn't dare raise his head, feeling his face heat uncomfortably.

"Sorry," he muttered, having to spit his mouth clear, but making sure that landed away from anyone's feet. "Sorry…"

"I forgot he used to lie like that about how he was feeling," Percival said thoughtfully, handing Gwaine a waterskin to pass to Merlin. "Here's his horse…"

Merlin took a mouthful to swirl around his teeth and spat again, humiliated and ill. He was used to his physical state being largely overlooked; that way he didn't have to explain how much weaker he was than the rest of the knights, over and over again.

"Can you ride?" the king said quietly in his ear, and Merlin couldn't help shying away a bit.

"I'll manage," he said, turning to fumble his boot into the stirrup. He almost tripped on it before he got his weight up and squirming over the saddle. His stomach lurched like it should be empty, but the contents settled when he slouched and gathered his reins. Blood throbbed in his temples.

The king whistled and signaled, mounting his own horse – not one Merlin recognized, or his own, though wariness due to unfamiliarity was distant. At least his mount started when the others did, and kept up as they picked their way through under-brush – presumably back to the path.

Still he was startled when he realized that it was the king who settled in next to him as they rode; usually Arthur ignored his presence and left it to him to guide his horse into position beside or behind. The king was watching Merlin more closely than he ever had, and he knew him.

That was deeply unsettling.

"I know it's a lot to take in," Arthur said quietly. "And I know that…" He paused, drawing the length of his reins absently through gloved fingers. "You're used to handling such things alone, and in secret. Maybe you'd even feel more comfortable with that, just now, but… you don't have to. I suppose you have ten years to learn that… you're so much stronger when you have friends that support you – not just companions who tease and laugh, but friends you can tell the truth, tell how you feel and ask for advice, and it helps. And we all fight together."

And the knights who rode with them, who surely had heard the king's words, didn't so much as snicker or roll their eyes to hear him speak so. To include Merlin with the fighters, part and parcel and not just attendant.

Merlin risked a glance, and when he discovered that the king was facing forward, away from him, he dared to look longer. Past the scars and the beard and the lines. And he felt something deep within himself – a wall? a barrier of some kind, at least – behind which he hid so much, begin to yield. He wanted it to yield, to release the internal tension of holding it in place, to let himself be free – and with this Arthur he could, he thought-

I wanted to tell you. I wanted to tell you…

But that would be cheating. That should happen with his Arthur. Someday when they were both ready.

A/N: Hopefully this one won't be too confusing… I'm going to stick to Merlin's pov, but there will be two versions of that which I'll preface with Past and Future, but as he's switched, it'll be his older self in Past, and his younger self in Future…

And, if you have issues with the concept of time travel in fiction, please message me and we'll discuss!

As for updating schedules, let's say… once every other week, as an outside figure. I've got to take this one slow and make sure I'm not creating any inconsistencies…