A/N: So this fic is for the Camelot_land assignment 'The Big One.' Because I'm crazy insane I'm attempting to put all 25 prompts of 500 words in one fic. The challenge closes on 16th April '14 so hopefully all of it will be up by then.

Comments are love and I feed off of them.

Prompts: The Beginning of the End, Valiant, Excalibur, The Crystal Caves, The Queen of Hearts & The Kindness of Strangers(Seriously, squint).

Standard Disclaimer applies: I do not own Merlin or any of the characters used here. I do not make any profit from this.

Enjoy.

Science and Faith

Chapter 1

Arthur hasn't seen Terra for years, let alone set foot upon it. He had an old-fashioned photo in his first bedroom on Mars from several centuries ago. It was taken from space, all lush greens under a thick, healthy layer of cloud. The view he has now, manning the cockpit of his Excalibur and waiting for landing instructions, is quite different.

The clouds are thin, grainy and tinged yellow. The blue is still there but lessened and not the clear, vibrant blue of before but more a murky navy. There is no green. Only brown in large jagged continents that cover more than three quarters of the planet's surface.

He is above Valiant now, hovering just out of reach of the fragile atmosphere. Every year the volume of rainfall decreases by point five of a percent. Every year landmass increases by four centimetres. And it is this husk of a dead planet his father has ordered him back to. This diseased shell of a planet, which Uther is determined to win back.

By the time Arthur's children die it won't even be habitable any more. But Uther started this war and he is stubbornly refusing to admit defeat. Arthur grew to resent him for it long ago.

Valiant will be his one day. He'll rule as king from Camelot, hunt dragons on Uther's behalf and wait for the day he can legitimately enforce an evacuation of this lifeless planet for good. It should have been done years ago, leaving, but there are so many people in so many colonies, no reliable census' since the conflict began and Uther's grip is iron-clad over his domain. Arthur suspects his father is paranoid the other kings are eager for his lands. One wasteland is the same as any other in Arthur's opinion, not all that much worth grappling over.

His comms screen lights up with bright red text to his right, information on the incoming vid-call scrolling across. He knows who it is and swipes his thumb up the warm glass immediately. Kings aren't used to being kept waiting.

"Arthur," his father's stony face greets him, translucent on the main view screen. He can't help but think there is a poetic symmetry when he compares the face with the scarred, ruined planet it is superimposed on to.

"Father," he replies expressionlessly, a private game he has played with himself since he was six.

"I have your arrival coordinates." It's unusual for Uther to handle something so menial, this tells Arthur something.

"You want to keep it hush-hush that I have returned," he states.

"You are the crown prince, Arthur," Uther says gravely. "A prime target for the enemy. Of course, I want to keep you safe." Prince first, not son.

"So why am I back here if it's so dangerous? I won't hide in Camelot until you end this war."

"It isn't a war." Arthur hears the silent 'yet.' "Conflict is the preferred terminology." It hasn't escalated to all out violence on both sides yet but Arthur doesn't think the riders and their pets probably see it so diplomatically. Half a century of raids and executions with no end in sight don't do good things for peace talks. It's a miracle they haven't attacked already. Arthur isn't confident it is a fight they will win.

"Besides," Uther continues, oblivious to Arthur's musings, "we are Pendragons. We do not end wars, we win them. They're getting bolder. Last week we caught one of their little snakes sneaking into the citadel. I need the crown prince here, Arthur, not gallivanting around the tropical biospheres of Mars with who knows how many questionable females." He studies Arthur, mouth clenched and eyes firm. "You have a responsibility." And there it is, that's the line that makes his blood boil. But he dips his head submissively, like always.

"Yes, father," he murmurs and immediately after the comm starts bleeping quietly as it picks up the transmission packets that contain his instructions and permission. Uther nods once, brisk and business-like before his face flickers.

Arthur is left staring at the sickly continent he will one day inherit. This is only the beginning. The beginning of his end.

The Excalibur is sprint landing capable – vertical thruster descent – but Arthur knows once he's feet down on solid ground he won't be going up again for a while if Uther can help it. Because he's such a flight risk. He puts off the inevitable as long as the regimented courtesy he had drilled into his brain as a child allows. He shivers as they slide through the ragged clouds, feels like it's tainting his girl with yellowish slime. The black quiet of space is replaced by the blinding glare of Terra quadrant two's midday sun – his view screen adjusts accordingly and he pats the worn padding on the arm of his pilot's chair affectionately.

He has spent a lot of time with his girl since he left, had hundreds of adventures. He would trust her more than any breathing, organic life form. She deserves a tune up and some love. He isn't looking forward to topping up her tanks with the semi-polyglute shit that passes for fuel on Terra now that most natural resources have run dry. He thought about leaving her back on Mars but he knew he wouldn't be going back, it felt too much like abandonment. Though he's reluctant, in the unlikely event he'll need her speed to,oh, win a racing bet or, say, run down a stowaway, he'll need her in top form rather than choking on her own fumes.

The world that greets him in the lower troposphere is all brown, flat and dead. Camelot, Valiant's capital and home to the reigning king, rises on the distant Northern horizon. Arthur rechecks the coordinates on his nav before accepting them, punching in a slow decline ratio and settling in to savour the weightlessness of flight. His girl glides soundless and smooth. He thinks about restricting autopilot just so he can bank and roll for the sheer fun of it. Instead, he uses the half hour of gentle travel to mentally prepare himself and take in the sights of his birth place.

He always liked Camelot, felt a connection to it. Maybe it's because Uther always said his mother loved it there and he's trying to forge a bond with a woman he loves but has no memory of. Maybe he's trying to force himself to like the place that will be his prison one day soon, just like how he has to force himself to like the man he calls 'father' these days too.

As they approach and the city becomes less of a three-dimensional speck and more of a dark outline, he can admit it has more personality than the land that surrounds it. The lower town sprawls out further south than he remembers with plenty of tilled fields filled with hardy produce. They are out of growing season for now but the ground is kept ready. The glorified mountain range is a hive of activity even from this distance. Much of the city's trade lies with the precious metals that can be mined from beneath the foundations, not to mention the Crystal Caves which are filled to brimming with precious jewels and other valuable products. Then there is the maze of decaying high rise buildings that doesn't fit with the rest of the city.

And the citadel itself is pure white stone which stands out like angel's wings against all the brown mud and yellow infection and crumbling brick. The castle is an ancient fortress that has somehow withstood the storms of time and the sun's battering, relentless rays. There are old folk tales that claim one of the last great sorcerers blessed the stone with the last of his power before he died, prophesying a long road of suffering and sacrifice that would eventually dawn a new age of peace. Arthur can't see that age any time soon though, especially with Uther stamping out any and all magical connections here in Camelot with his dogged campaign. That's not to say Arthur doesn't believe there's some truth to the stories, the stone has always gleamed unnaturally bright – not that he'd ever mention that to his father.

The remains of the scientific centre, a great, hulking monstrosity, are tastefully hidden behind one of the larger mountains. But that is not where Arthur is heading. He is going straight to the only active airstrip behind the castle. The Excalibur will be housed and maintained in the royal cavern directly beneath the north portion of the citadel. There is no need for the scientific centre any more – not that an scientists stayed long on the planet to run it after the first wave of relocations, there was too much promise of discovery on the new, distant colonies.

And they have no need for a space port. What few visitors they do receive are foreign dignitaries who the royal family will house personally. The only other air traffic is the city guard and they are likewise stationed in the cavern. If people are still on Terra it's either because they don't want to leave or can't afford to any more, so there isn't anything other than the annual shuttle to Mars which is extortionate. And there's no need for a public transport network, where would people travel? Traders who have their own ships are, by law, nomads and belong to no country. Everyone is at war with everyone else and what small percentage of the desert wastelands is inhabitable is crawling with any number of terrifying dragons and other dangers too horrifying to imagine.

By the time they've breached the city limits, the Excalibur's silver belly is nearly touching the dilapidated roofs of the skyscrapers. It's an odd mish-mash of history, even to Arthur who grew up flying these streets. The lower town is squalor and mud and poverty in its purest form, where you live off of what you grow yourself and you help your neighbours so long as your own children won't starve. The upper town, more often referred to as the Inner City, is all giant, creaking concrete structures, somehow still standing strong as they sway ominously in the dusty wind. And the streets beneath them are cracked rubble and overturned tarmac. It's an entirely different kind of wasteland to the one outside the city boundaries, but it is just as bleak and Arthur cannot fathom why his father fights so hard for it. This can't have been humanity's destiny, can it?

The Excalibur sails around the taller spires and towers of the castle, alone in the sky, before circling the short airstrip, which is no more than an oval of bulbs with two long, straight arms reaching out parallel to the castle walls. They aren't even lit at this time of day. His girl touches down gently, he barely feels is in the comfort of his chair – he's proud of that, it took him months to calibrate everything just right for the perfect result.

His pace is reluctant when he heaves himself with a great effort from his chair after checking and rechecking every instrument has deactivated properly – moot, of course they have, he's on the Excalibur. The main hallway suddenly feels far shorter than it ever has before.

His girl is big enough to house two guests as well as himself and still outrace an Utopian Defence Speeder – a light-weight stealth ship the fleet use, supposedly the swiftest of its class. Although he does usually end up kipping in his chair when that happens. She's built for distance travel of the on-planet variety rather than space-faring but she can cope with that too. She's slim and streamline for speed through air pressures and wind currents rather than the void of the black. Her wings are long but angled sharply, like blade tips so he can easily pass between buildings if need be. She's not built for luxury, more quick take-offs and acceleration but Arthur knew that when he bought her against his father's wishes.

The Pendragon crest of a roaring, golden dragon – the irony isn't lost on Arthur – is mostly hidden by the ruddy reddish-brown colour of mars dust now but the shell itself is a decorative red. The dust dims it a bit but it's still visible.

Gwaine is waiting for him when he slides down the metal ladder that extends from the Excalibur's belly – she isn't large enough to warrant a hydrolic ramp and evacuation tubes are damn expensive. He is a welcome sight. Gwaine has been a good friend for a long time. They grew up together – the only young children in the entire citadel at the time.

They haven't seen each other since they were young...supposedly. Of course, Arthur isn't supposed to know that Gwaine tails him for about a month every martian year across the red deserts. But he does, because Gwaine usually does it from the back seat of whichever Rover they have 'borrowed' from the labs.

As far as Uther knows they haven't seen each other since childhood though. It is going to be a hard act to keep up. No more back slaps or secret jokes for a while.

It's going to be strange reacquainting himself with all of the people he left behind and actually hasn't seen over the past years. Leon, for example, will still be a member of his father's household guard. Arthur wonders for a second what assignment he was given after his own hasty departure.

He turns his attention to Gwaine as they start out across the sparse landscape and back towards the citadel. Guards and techies are already sprawling out from the caves below the castle to come and collect his ship.

"Any news?"

"Oh, nothing of interest." Gwaine replies, eyeing him sideways. Arthur knows to wait for the gossip. The silence stretches but Arthur has too much experience to let it be tense. Eventually Gwaine huffs and says, "You're no fun any more. Anyway, word is the King's got himself a dragon rider shackled up all medieval down in the caves."

Arthur already knows that, or has guessed it from his father's implications during his transmission. He knows Uther won't have killed him or her, they hold far too much valuable information for that. It's interesting that he hasn't made it common knowledge, not even around the castle. He allows Gwaine to continue uninterrupted – he'll just end up going off on a tangent of innuendo and ghastly, horrendous ideas if he is distracted.

"Most of us were away on a raid at the time. There were reports of a lizard in the mountains getting near to the city. Sent three whole brigades and heaven knows that's most of us nowadays. We get back, scorched and empty handed and there's rumours flying about the castle of spies and intrigue." His eyes are slitted melodramatically, arms slinging everywhere enthusiastically. "Course, when we asked no one would tell us a sodding thing." He sniffs here, picks a spot of dust from his sleeve – a useless pursuit – and moves on like he hasn't been overlooked and the story actually isn't of any import.

"And guess whose Queen has finally been chosen, my liege?" Gwaine bows low, arm flourishing out behind him. Arthur hides the wince behind a disinterested cough. He'd known there were other reasons Uther wanted him home. Hoped this wasn't one of them though. Unfortunate.

"Who is she then?" He asks, increasing his stride length and throwing his head back a little. Gwaine can appreciate the power of a good strut.

"Name's Guinevere. Daughter of a metal worker from the lower town. She's been given the Hearts. You'll like her, easygoing and kind, as the name suggests. Pretty too. Haven't had the chance to bed her yet but I'll let you know how that turns out too." Arthur gets an elbow nudging him in his side with that and he can't help the laugh that strangles out of his throat. Poor girl.

The council chooses a suitable spouse for every heir born. It is an archaic tradition but it seems to work. There have never been records of an unhappy marriage. But kings and queens write the records – dictate them anyway – and they aren't going to want their legacy dragged through the mud. The arrangement benefits the health of the society though. The Chosen is always low born, never from inside the citadel and they are picked for certain attributes. Arthur's mother was the Queen of Diamonds, made royal by her outstanding beauty. This Guinevere, his Queen of Hearts, will be kind and compassionate beyond all others. Could be worse, he could have gotten a Club, the smart ones are always condescending.

Uther is waiting for them atop the stone steps in the courtyard. Arthur had forgotten how daunting walking through the iron gates can be. The spires of the castle are endlessly high and the gnarled gargoyles stare down grotesquely. It's unnerving. Not to mention his father's unwaveringly cold eyes.

Arthurs meets his queen-to-be that night at dinner. Uther has the banquet hall prepared for a welcoming feast but it is all a display of power, the decadence he can summon with a stomp of his feet. There is only the three of them sat at the table – its top is all polished wood and gleaming silver – and the honour guard at the perimeter is minimum. But Arthur can see shadows behind the tapestries up in the gallery and he doubts Uther's paranoia would let them be too far. Gwaine is suspiciously absent from any post.

She is as kind as her Hearts title suggests. She is calm, except when she stumbles over her own insecurities – 'Call me Gwen. Unless that's too informal. You can stick with Guinevere...if you like. Or if that's too long? Gwen's fine' – and understanding. She seems to empathise with Arthur's situation without him having to explain with more than heavy eyes and forced pleasantries for his father's viewing. The whole thing is unfortunate in some ways, he thinks instantly that they could have been good friends. She definitely isn't the worst future spouse the king and his council could have picked.

There is much conversation over the weather and Uther's dietary changes but little about the economic climate and nothing of the 'conflict'. It's probably being saved for a later time when they are alone. Arthur suspects Uther will want to gloat about the famous prisoner everyone's been so cagey about.

He's right. As soon as as he places his dessert spoon quietly down – it's a luxury but they are still royalty – Uther stands, meets his stare meaningfully. Arthur bids Gwen a good night even though the sun has barely set. She catches the hint gracefully, like she has been playing political chess her entire life, and brushes her lips to his cheek before leaving them. Arthur's following the king's swift, purposeful stride before he can process that they are moving. There is the urge to half trot to keep up, like he used to as a boy, but he's a man now, a prince, with pride and honour and longer legs. Even though they burn slightly from the disuse of a weeks' worth of space travel he lengthens his steps, grits his teeth and refuses to complain.

Arthur knows they are heading for the caves when all the windows are suddenly gone. His memories of the castle are faded and he has only been down here once or twice but it is the only logical conclusion there is.

Occasionally, maybe once a year, Arthur's dreams will return to the expanse of caves that curl and maze beneath and between the foundations of Camelot. In these dreams everything is dark and dingy and there is water dripping. The bars of the cells are mouldy. In reality, they are nothing like this. The sconces on the walls are few and far between but the light from the flames flickers on every crystal, shining a bright spectrum edged vivid blue when they pierce through the other side which reverberates everywhere around the caves. The guards stationed down here call it 'ghost light'.

The crystals themselves are a mystery, even to the sorcerers of old. They have an unknown property that allows them to restrict and bind magic entirely, leaving sorcerers in the cells completely helpless. Unfortunately, it does the same for most technology, hence the archaic lighting system. The crystals used to be half buried in the dark stone until a traitor wrangled one free of the stone and used its dagger edge to slash his own throat. Since then all crystals have been removed from the cells and instead are piled regularly between each cell out of reach. Uther ruled it too dangerous to remove any of them in case their effects were decreased – Arthur still has one lodged behind the original oak dresser in his castle bedroom, not that he's had time to check it it's still there after all these years.

The caves smell of rot and disease. The cells they pass are clean though. The stench and the tension are all memories, like screams echoing down the empty passageways from years ago, and they make Arthur clasp his hands rigidly behind his back. Not many of the cells are in use – the soldiers of Valiant are under strict instructions to exterminate all dragons and their sorcerers without question these days.

The cell Uthere gestures him towards, like he wants to forcefully push him to the bars but wants to avoid skin contact, is directly opposite one of the exit tunnels. Although he has never practised the escape, Arthur is aware of all three emergency routes out of Camelot should he ever need to run from an attack they have no hope of winning. He eyes it cautiously, breathes the stale air into his lungs from its mouth that would be fresh and cold only one hundred metres from where he currently stands.

"Talk to him," the king orders, no nonsense, flicking a key at his chest which Arthur palms instinctively. There are no guards. Then he is gone, whisking away in a swirl of royal fabric and leather – another rare commodity that displays his wealth.

The sorcerer is hunched towards the back of his cell, glaring mournfully at the heap of crystals in his line of sight and playing with a stone – strong, nimble fingers swift and sure even though he isn't paying attention to what he is doing. The bones of his face are sharp beneath his pale skin – the trickster lights make it look translucent, ethereal. He's all cheekbones like dagger slashes, plush lips like temptation and dark curls like smoke. And eyes. His eyes are innocent and wide like a child's but the blue is deep like the oceans of legend, clouded with secrets and danger. Maybe that's the ghost light too.

"They've sent you down here to question me?"

"You're a dangerous assassin, not deaf. I know you heard."

"Your king's inquisitor couldn't stab the secrets out of me, why do you think you can, prince?"

"You know who I am," Arthur states.

"Everyone knows who you are."

"I could snap you with an unarmed laser gun," Arthur threatens, violence is his default when he starts to feel his temper bubbling.

"I could snap you with less than that."

"In here?" Arthur all but snarls. The sorcerer lowers his head, concedes the point. The small victory makes Arthur brasher. "You got a name?"

The sorcerer considers, eyebrows lowering confused. "No one's asked me my name since I've been locked up down here."

"Then no one you've spoken to has any manners."

"The king questioned me himself."

"As I said."

That causes a change in the way he's being considered. "Merlin," he says clearly through thinned lips, eyes darting from one end of the bars of his cell to the other, searching for guards.

"Arthur," he replies, although the sorcerer already knows this. "And there aren't any down this far."

Merlin doesn't reply for several minutes, instead he sits there, hunched in his corner and considers Arthur with scrupulous, unblinking eyes, the blue so bright it glows. When he speaks, it's slowly like he is considering and reconsidering every word he says, worried Arthur will be misunderstood. "You don't agree with some of the king's philosophies?" Arthur notes that there is no mention of their relationship, their shared blood.

"Some of them," he shrugs, like this isn't edging towards treason. Like he isn't discussing delicate matters with the enemy.

Merlin slides to his feet – Arthur thinks it's a monumental moment the way he does it so gracefully, eyes still lingering on Arthur's face, but then he stumbles on his first step towards the bars and Arthur coughs to cover his snigger.

"And the war?"

"Conflict," Arthur automatically corrects. One long-fingered hand extends from Merlin's haggard cloak, flicking at the air non-consequentially. He is taller than Arthur thought he would be and he takes an involuntary half step back as he approaches despite his stick like limbs. Sorcerers are known for being cheaters and liars.

"Whatever you want to call it," he says although his eyebrows twitch, forehead creasing, giving away his true feelings on the semantics. "You have your own ideas about it?"

"So what if I do. The King is the King. His rules are absolute."

"You think we're all killers?"

"I've been back on Terra less than a day. I don't know what I think yet." Which isn't exactly true. It isn't like he has had his head down a Marshian's burrow while he was on Mars. He knows what has been going on back here at home. He knows how unfair he thinks the entire catastrophe is. He knows he doesn't agree with his father. He knows it isn't justified. But speaking out against the king is an entirely different matter than thinking a little outside of his iron box of laws. It's obvious that Merlin reads his lie as well, his chin drops and he hums quietly to himself.

"Would you help me if you could?"

"My duty is to Valiant," Arthur replies immediately.

"And slaughtering my people, is that for Valiant or for the king?" Merlin allows a silence to settle heavily between them before he appears to come to some sort of decision. He draws himself up to his full height, a few inches above Arthur's own respectable stature, and breathes a long, deep breath, like he is about to jump from a very high cliff. "Do you know what a Debt is?"

Of course he does. Every child hears the stories and fairy tales that come with it in school, the lore. Arthur is no exception, although his teacher was much more secretive due to his father's aversion to such things.

"It's magic," he says, injecting as much spite as he can into the answer.

"It's old magic," Merlin specifies, leaning against the bars but making no attempt to reach through them. This close the shadow under his cheekbones looks hollowed out like he is a starving man and the blue of his eyes is glittering and earnest. "I'd be in your debt if you released me from this prison."

"You think I'm an idiot?"

"You could ask me anything you wanted."

It's the kind of deal his father would be interested in hearing about. But this is something between himself and Merlin. The rebel inside him, raving through his veins with excitement at such an opportunity loudly, ricochets around his skull and pounds in his chest.

"How the bond works," Merlin whispers and Arthur leans closer to hear him, watching his lips quiver as he talks. It's true a squad of fliers would recapture him within the day if he were to let him loose.

"How many of us are left," Merlin breathes, Adam's apple bobbing in his throat. There isn't enough air in the cave, Arthur feels like he's drowning, being seduced by the idea. His father will think he's trying to prove himself, that he has a plan, confident of the easy recapture of his prisoner.

"Where the nest is," Merlin murmurs, his breath ghosting over Arthur's clammy skin, ruffling at his fringe of hair.

"Magic doesn't work down here," Arthur hears himself mumble.

"My magic doesn't. Debt magic is of the earth and the air."

"We'll just hunt you down again. Why would I want a Debt from someone who'll be back in here or dead this time tomorrow?" Arthur reasons weakly.

"Then why not? If you're so confident you'll catch me again, what have you got to lose?"

"I don't even know you," Arthur says even as he feels the idea catch inside him, tempting him past all reason.

"Think of it as a business arrangement." Arthur hadn't realised how close they were until now. Merlin's lips quiver and he feels the vibration like a tornado against his own. He shakes his head minutely, tries to clear it. "A kindness then," Merlin amends, seeing his discomfort.

Arthur gulps past the sawdust in his throat, ignores the rawness there. Forces his lungs to expand. Watches Merlin's eyelashes flutter at the resulting puff of air.

"A Debt then?" He confirms finally.

"A Debt," Merlin hisses gravely back.

"How do you make the contract," because even this deep in over his head Arthur's not an idiot. He knows magic is entrenched in bindings and ceremonies and traditions.

"You're sure?" Merlin asks one more time, which strikes Arthur as odd because surely he should want to be out of here like a man from the desert craving water.

"No," he laughs, the sounds clapping like thunder off the quiet walls. "But do it anyway." He chews on his lip, stares at the sorcerer whose nose is peaking out through the bars, almost brushing his own.

Merlin dives forward, quick like a viper attacking. The lips against his are soft but unyielding, crushing against his mouth. It isn't a kiss, not further than the anatomical sense of the word. More like a fight. Then there's the rumbling shaking the crystals and the loose stones, rattling them across the floor of the cave. It vibrates up through his boots, juddering up his spine, drumming in his skull until his teeth clack aggressively with Merlin's. The jolt of power across his skin and through his blood feels like electricity, buzzing angrily until it settles at the harsh point where they are connected.

When Arthur wrenches himself away, it is to find Merlin looking at him expectantly. He swipes the key from his pocket, convinced one of the guard higher up will have heard all of that noise. The lock is stiff but clicks open when the right force is applied.

He juts his chin towards the mouth of the cave behind him as Merlin slides from his prison, sweeps his palm across Arthur's torso as he goes gently. "Always turn right whenever there's a path. It'll take you out into the inner city, Sector B4."

"You don't want your Debt repaid?" Merlin asks, unsure, steps hesitant as he inches towards the dark unknown.

"You'll be back here within twenty-four hours. I'd like to think on it," Arthur says assuredly. Cocky. Quirking a smile. He isn't expecting the grin he gets back.

"Suite yourself," Merlin shrugs, disappearing into shadow.

Feedback would be appreciated.