Disclaimer: The plot and characters of Doctor Who are not mine, and this story is not for sale or profit. (But if, by some miracle, it should turn out that I was right, remember, I totally called it!)

A/N: This is a cheesy bit of head canon based on a play on words that has been brewing in my brain since "The Girl Who Died"; after "Face the Raven" it all just came boiling out onto paper all at once. I don't know where the show writers plan to go from here, but I refuse to believe that Clara is really, finally dead, and this is my own personal theory on how things might have actually gone down during off-screen moments when we weren't looking. I don't consider it AU, because you can't prove it didn't happen! (Denial is not just a river in Egypt…)

Pairing: Twelve/Clara

Warnings: Spoilers for Season 9 of Doctor Who

DIAMONDS ARE FOREVER

PART I

A continuation of "The Girl Who Died"

"What's a diamond, after all?" the Doctor mutters to himself, punching a numeric sequence almost defiantly into the TARDIS console. "Compressed carbon, sure, sure, but there's also some very sound scientific, mathematical and linguistic arguments to be made for a rhomboid polygon in a two dimensional plane, so really, all things considered, any four-sided geometric figure viewed from the correct angle would qualify... technically…"

He pulls a few levers, mostly for something to do with his hands. Then he grips the edge of the console as though trying to keep from falling off of the floor onto the ceiling. The world seems to be shifting uncertainly around him, even though the TARDIS is flying smoothly for once. He stares down at the console keys, not really seeing them. He has been pacing almost manically around the control room since Clara went to freshen up, eager for a wash after nearly a week in the company of Vikings – leaving him alone with his thoughts. And no one to manage his conscience.

Pushing away from the console, he unclenches his fist and holds the object he has been clinging to up to the light, examining it warily, like an alien creature he is not yet sure he can trust not to go for his throat. Thrilled and horrified by what he is about to do.

Justifications swirl around the doubt in his head and in his hearts. Every law of time, ever rule of ethical conduct, every vertebra in the back bone of the morality that has guided him during his travels, groans under the weight of what he now dares to contemplate.

All the while he is tracking Clara's movements. He could watch her on the monitors if he chose, but there is no need. He knows her. He can see her in his mind, and is beside her step by step in his imagination as she makes her way to her room.

As he watches now she…

...steps into her room, and out of her clothing, pausing before the mirror (because she's Clara, and she will).

Now she's in the shower, and she takes her time, because it bothers her for some reason that he apparently can't tell when she has bathed (an extra four point seven six minutes is wasted merely enjoying the steaming hot stream of water flowing over her body).

Almost too soon she's back in her bedroom, warm in the old faded flannel pajamas she keeps aboard at all times (her favorites, and it pleases him to a ridiculous degree that she has always left them here, even during her misadventures with PE). Her hair is still damp, but her eyelids are drooping with fatigue and the pleasant soreness of her muscles.

So now she's curling up on her bed, sighing contentedly as she eases her grip on the waking world and slides down into sleep, a little smile on her face that he flatters himself he had some role in putting there…

The Doctor sighs himself, and checks the time index unnecessarily. He knows she will be asleep by now. He is stalling, and he knows it, and it panics him, because time is running out, always, always running out for Clara. Tick-tock! Tick-tock! Still he pauses, hesitating one last time with his fingers poised over the controls. Then, swallowing back the thundering of his hearts in his throat, he flips the switch under his hand with an air of finality, executing a silent command.

He knows the way to Clara's bedroom by rote. It has moved from the realm of memory into a force of instinct. He could find his way to her blind. But he keeps his eyes wide open, and endures a harrowing cycle of doubt and resolve with each step. Both deepen with every footfall, until he stands outside her door, full of dreadful certainty.

This is as far as he has ever come. Never inside. It isn't a matter of respect or privacy. He suspects that she knows that he has been all over her bedroom on Earth, sating his curiosity with an utter disregard for discretion and a fine tooth sonic comb. But there is such a thing as too much temptation. Here on the TARDIS, within his own domain, what lies beyond these doors is forbidden to him. It is a rule he made long ago. Good men don't need rules. And that is why he doesn't trust himself with her.

Turns out he was right to worry.

But he is here now, and the rulebook is in metaphorical tatters at his feet. It feels almost a sin to have come this far and go no further.

The door opens and he can hear the quiet hiss slithering menacingly from the ventilation ducts. He smells the faint tinge of the anesthetic gas flooding the room. Not much, just a little, as if that makes a difference, just enough to hold her asleep and unaware – just enough so that she won't wake until he is ready to face her. The gas doesn't affect him, but then, he's not human.

Clara obligingly doesn't stir as he steps into the sacred sanctum. She lies curled up in a nest of blankets, half on her stomach, hugging a pillow to her chest. He pauses just inside, cocking his head to one side and blinking rapidly as he examines the brand new and curious sensation that is jealousy of a pillow. To his knowledge, it is a first. This is why he keeps them around, all these wondrously brief, brightly burning little will-o-the-wisp human creatures, why they are so very important: even after more than two thousand years, they are still able to give him new experiences.

But that is not what Clara is for. Not anymore. Maybe it never was.

Pacing slowly forward, he sits down on the bed beside her, and she remains still, though a humming little sigh escapes her. She nestles more deeply into her bedding, contented as a purring cat, pulling the pillow tighter into the curve of her body and pressing her cheek against its softness. Inane jealousy flares again, and, bolstered with the daring of the unobserved, he slides his hand between flesh and fabric, so that he is cradling her cheek in his palm.

It is his turn to sigh again, his fierce eyes softening with the warmth radiating from their contact. All his longing and denial wind themselves tight around the stab of his guilt, the better to spiral painfully down between his hearts like the blade of a corkscrew, to lodge there with a thousand others.

He knows he should leave now, before it is too late. Just as he knows he will not.

His eyes trace her face, and his thumb rises of its own accord to brush the full swell of her lower lip, remembering what it felt like against his. He recalls it with a startling clarity usually lost over the edge of regeneration:

The surprise of that sudden unexpected contact, so eager, tenacious, just a little bit hasty in a fit of nerves and daring.

Hard on its heels, a different sort of surprise – that it affects him, kindling a spark in his blood, fascinating him, enticing him, so that he cannot push her away, and stands at her mercy until she sees fit to release him, leaving him tongue-tied and awkward as an untried boy.

And forever after that it is surprise after surprise, as he is assailed time and again at the most inconvenient moments with the urge to do it again.

Trumped only by constant unflagging surprise each time he finds it somewhere inside of himself to resist.

The odd irony is that they have never shared a kiss. Oh, he remembers distinctly how their mouths fit together, so neatly, so rightly, that it seems all the more a shame they never tried again. But it was never this mouth – neither hers nor his. He lost his when he changed it to something so very different, and the Victorian governess died because he failed to save her. Though the soft pink mouth ghosting warm breath against the pad of his thumb is so very much the same as he remembers, it belongs here and now to a twenty-first century school teacher, and she is somebody else altogether. Any chance for a second kiss is gone forever, lost like so much else before.

Even so, it did happen, and the memory is branded on his hearts. So is it any wonder that he cannot help but wonder, as he presses down on her lower lip, exposing just an edge of pearl white teeth, what it would be like to have a second first kiss? What it would it feel like to touch these lips with his new mouth? He wonders if she would taste different now, if he were to tease them apart with the tip of a different tongue, and whether he would ever be able to tell whether the difference lay in her mouth or in his.

He tears his eyes away and his other hand opens to reveal once more the object he has secretly carried away from the Viking village, carefully concealed from her these past two days of apparently overbearingly Scottish brooding. A small, bone-colored computer chip lies before him, all unassuming innocence and temptation; just like Clara, just like a meant-to-be match set lying here side by side.

It is a Mire battlefield medkit.

Flipping it up and taking it by the edges in his thumb and forefinger, he turns the little square on a forty-five degree angle and purses his lips.

"Humans and penguins," he mutters with an edge of derision to hide the way his hearts flutter, "chucking rocks at each other to declare their devotion…"

He is referring to that quirky little Earthling pair-bonding ritual that involves presenting one's desired mate with a diamond, asking her to be his forever.

"Sort of a diamond. Technically a diamond. Diamond-shaped, anyway. And definitely forever…"

There had been three undamaged Mire helmets for him to salvage from. Three med chips, reprogrammed for human beings. He'd given two to Ashildr. No sense in leaving this last one lying about. It might fall into the wrong hands.

"Immortality isn't living forever. That's not what it feels like. Immortality is everybody else dying…"

Wrong hands, yes. Like his for example.

"…she might meet someone she can't bear to lose. That happens, I believe."

But is it really so wrong? So unfair? Clara once said that she had been born to save him; that she blew into the world on the most important leaf in human history, and that she was born for his sake…

Selfish!

Yes, it was unfair – to Clara. Clara was so much more than that, so much more than just him, or his petty need to stem his loneliness, or his desperation to see the universe through mortal eyes … so much more…

Yet even as he acknowledges this, her words echo in his head from beneath dark waters of the Fisher King's tomb, sliding his conscience sideways and slipping by.

"You owe me! You've made yourself essential to me. You've given me something else to… to be. And you can't do that and then die. It's not fair!"

"Well is it any fairer to me?" he whispers to her, transfixed by the fan of her eyelashes against her cheek where she lies so peacefully asleep beneath the storm of indecision raging around the hurricane's eye of terrible, shameful certainty above her. He closes his hand tightly around the med chip again, clutching it like a talisman in one hand, and cradling Clara's cheek in the other. A perfect match set. "Is it, Clara?"

"If you love me, in any way…"

He relaxes his hand again and looks down at the chip crouching in his palm. Like a spider, he thinks, biding its time as its web trembles with the desperate thrashing of still-struggling prey that doesn't know its fate is already decided.

No matter how he rationalizes it, a computer chip is not a diamond, and he is going to get this little ritual wrong very, very wrong. But then, he is no human, and he has no intention of asking her. Because she might say no. Or even more terrifying, she might say yes.

Once she realizes what he has done…

…when she begins to notice the years passing, but the little lines around her eyes never deepening, the rich dark sheen of her hair never graying, and begins to wonder, begins to question, begins to suspect…

…when loved ones begin aging, sickening, withering, dying, leaving her behind, forever alone with the cumulative weight of their loss…

…when the world goes on changing, marching steadily on, and she loses pace with the flow of humanity around her and is left by the wayside, a stranger in her own timeline, forever and ever unchanged…

When she understands what he has done to her, she may never speak to him again, may never see him again, may never run with him again. It is terrible, crushing thought; because she has become essential to him. And it is a risk he is willing to take.

With this diamond that isn't a diamond, he does not ask her to be his. He only demands that she continue to be, because she is essential to him and he cannotbear the alternative.

He holds the chip above her skin as the air seems to crackle with portent.

"Clara, my Clara… forgive me…"

He presses the chip to her forehead, and in an instant it has burrowed inside, the skin welling up and sealing deceptively around it, as though nothing at all had changed, instead of everything - as though she has not gone from being a dying mayfly, to functionally immortal, between one beat of her heart and the next.

He doesn't watch. Instead he has already bent double over her, before thought or circumstance can get in his way. This time he is the one kissing her without permission, stealing their second first kiss, eager, tenacious, just a little hasty with nerves and daring, hungry and hearts-broken with the bittersweet surprise that she tastes exactlythe way he remembers.

He draws swiftly away and rises, backing away. His mouth tingles with the lingering sensation of contact, burning with even greater hunger now that he has sampled the feast. But he no longer has the right to touch her so familiarly, now that he has violated her so thoroughly; stolen her choice. Robbed her of her death. There is shame in that burn as well, shame at his own selfishness, disgust at his cowardice, anger with his own weakness.

But he feels no regret.

"I…" he swallows against the terrible ache inside, which he has just recognized as that most terrible of oppressors – hope – and tries again. "I love you," he says to her still, silent, suddenly eternal form.

It has never been more true, because now he can risk acknowledging it, and as he gives it voice, he finds it bigger and more terrifying and more glorious than he ever suspected. His hearts contract painfully in his chest as he backs towards the door.

"When you figure it out…" he breathes, "oh, my Clara… never forgive me."

TBC in Part II

A/N: This bit could have been a stand alone little one shot, so feel to treat it as such if you so choose; however, to me it feels incomplete without being book-ended by Part II. You decide. Now review, review, my pretties! Muwahahahaha!