Title: Weapon (the unexpected key to the universe remix)

Author: TardisIsTheOnlyWaytoTravel

Story Summary: Doctor Who/Buffy crossover. Something's wrong with Martha Jones. The Year That Never Was has been undone, but the universe is unlocking all around her, and sometimes she isn't sure which reality is real anymore. Fic is somewhat angsty, but ends well.

Author notes:

Remix of Weapon by Poetry. (on archiveofourown dot org) Written for Remix Redux 8.

Weapon (the unexpected key to the universe remix)

It's been three months since Time turned over and the Year That Never Was ceased to exist, but reality is subjective and to Martha Jones it sometimes seems that it's this existence that isn't real and it's That Year that surrounds her still, drowning her in its death and terror and desolation so that when her mind wanders it's that broken, bleeding world suddenly before her eyes.

She's glad that all the death and suffering never happened, but it also negates all the bravery and sacrifice that took place – the Rewind has almost made it all pointless. No one will ever remember what some people gave, the compassion and determination they displayed, except for a dozen people for whom That Year is as real as what has replaced it.

The Year That Wasn't haunts her thoughts and dreams and well-honed instincts, so it doesn't surprise Martha nearly as much as it should when she steps forward carelessly one day and finds herself in the nightmare world of devastation.

For a moment every muscle locks up so that she can't breathe, can't think, just stares around at the blackened burning landscape hearing remembered manic laughter in her head.

Then the wave of terror engulfs her and she takes a step back in horror, only to find herself back in the other quiet comfortable world as though she were never away.

Martha wonders if she's going mad, but if this is madness then it happened long before this now.

o0o o0o o0o

It's been six months since the Master doomed the world and Martha's been running all that time, only the necessity of her mission and her blazing faith keeping her going when exhaustion, dull terror and a soul-deep grief weigh her down.

In that six months though no one's ever come this close to capturing her, and she knows that if they do then it's all over, that the world will never be saved and that now will be for ever and ever.

And that is the most horrifying thought Martha has ever had in her head, so she puts on a burst of speed she didn't know she had in her, but the sound of heavy running footsteps is still too close behind.

"Oi, Martha Jones!" someone shouts with cruelty in their voice, and Martha closes her eyes and wishes with all her might that she was somewhere that none of this had ever happened.

Her foot comes down on grass.

Suddenly Martha is in the world that she has missed so much, and it's just dull and ordinary and unbroken and so wonderful that Martha can only stare around with tears running down her face.

She's getting a lot of stares – she's wild-eyed and crying and covered in dust and dirt and some blood – so she staggers to the nearest bench and sinks down.

She thinks there's no way it can be real, it can't be, but she drinks in the sight of the sun and blue sky without a fog of smoke and poison to obscure it, and the smell of grass and clear air and somewhere, someone cooking, as though she'll die without it.

For the first time in six months, she's safe, and here in the gentle peace of the park she falls asleep and sleeps for hours.

When she wakes it's late afternoon, and she steals a hot pie from a small bakery and eats it, savouring the taste and smell and the moment. Eventually she thinks of duty and need and honour, and finds herself back in the world of the Master. But her pursuers have long moved on, and Martha spends the night in relative safety.

And for the rest of That Year she carries the memory with her, of the world untouched by evil and horror.

o0o o0o o0o

With doors to another reality opening for her somehow Martha doesn't pay much attention to what is and isn't possible these days, and starts to find that locks do not deter her any more. Even the security system at the hospital has only to feel her presence and the lock beeps open, as though Martha has some universal key she doesn't remember being given.

One morning she cannot find her car keys no matter how she searches, and in utter frustration tells her car to start without it. And by some fantastic feat, it does, and Martha wonders why the world's boundaries seem to keep blurring around her these days.

She'd like to blame the Doctor, but she's pretty sure the problem is herself.

o0o o0o o0o

It's that night that she has the dream.

She's older, and Caucasian, and some detached lucid part of her mind wonders if this is some twisted psychological element of herself coming into play, granting some subconscious desire to be treated like any white person.

Screw that, she thinks, she's not going to let bigotry dictate her internal world as well as the external one. She decides its just one of those things that happens in dreams, and refuses to analyse it any further.

She's maybe in her thirties at the most, lying on the ground with a distraught one-eyed man bending over her, and a bunch of others crowded around. They're all very familiar, especially the flinty-eyed blonde woman and the redhead crying next to her.

"I'm sorry, Xander," she says to the man by her side, smiling weakly, with such apology and sorrow in her tone. In the dream she is so, so sorry to be leaving him alone.

"You'll – you'll be okay," Xander rambles, his voice full of anguish, and it's clear that he hears the lie in his voice. He doesn't usually do this, he's been through to much, but this is her and he can't say the truth aloud this time.

Willow – and Martha loves her very much too, in the dream, although in a different way – steps forward and kneels to put a hand on Xander's shoulder. She's clever, Willow, and powerful, but she knows when something is beyond even her. There are boundaries that should not be crossed, not for anyone, and Willow learned that the hard way. It's part of what makes her wise.

"Xander –"

"No!" He cries out. "Don't say it!" His voice is full of fierce anger and desperation.

Martha looks around for someone.

"Buffy?"

The blonde woman steps forward, and behind the flintiness – Martha knows better than to pay attention to the mask – her sister's heart is in her eyes and it's breaking. And it's as painful to see as Xander, because Buffy has already lost so many people she loves. The curse of the Slayer isn't that you die so young; it's that you see so many others die, so that however much you might rage against the darkness, when it finally comes, some tiny part of you is glad that all of it is over.

Martha can see that in Buffy's future, in some part of her that is deep and intuitive and far more knowing than she is, and she knows that this, here and now, has only made that inevitability even more certain.

"I'm here, Dawnie," and to everyone else Buffy's voice might be steel, but Martha can hear the tears in it.

"Take care of Xander for me, okay?"

Both of them had feelings for each other, once, at different times. Maybe they'll find something in each other to keep the wilds at bay once she is gone.

"Take care of the Xan-man, right," Buffy agrees, her voice choking a little on the words. "I can do that for you."

Martha turns her head to stare into Xander's eye, and there is a wordless moment, in which she shows him everything she is and feels and he does the same.

"Watch out for Buffy," she says softly. "Willow," she looks at the witch whose eyes are pools of sorrow, "keep the darkness away."

And as she glances back at Xander she closes her eyes with the last of her control, so that he doesn't have to see the light leave them.

o0o o0o o0o

The hospital politely suggests that Martha might want to take some leave from her internship; it's perfectly polite, and since U.N.I.T. let them know a tiny fraction of what she went through there's genuine compassion in their eyes; but it's one more thing on Martha's mind, together with the fact that she nearly gutted someone with a scalpel when they took her by surprise. She caught herself in time, and nothing really happened when you look at it that way, but Martha can see what might have been, inside her head, and knows that from the other angle something happened very much indeed.

It's PTSD, she knows, and something more eating at the edges of her mind, but the textbooks danced over the effects and never said what happened to the person involved, and Martha knows now that this is a failing and a mercy for anyone who reads it.

Her entire world is falling apart, after all her efforts to put it back together, and part of her knows exactly what's going on but the rest of her is too afraid to face it. All she can do is try to exist, until her mind can being her face to face with it.

In the meantime Martha experiments.

The first day of leave she takes a deep breath and flips everything to rearrange it in her mind, and suddenly she's back in the Year That Never Was, the world that never happened.

She stands and looks around her, just breathing, and for the first time she's calm and in her mind there's balance.

She can't stay here long – she doesn't have a perception filter anymore – but as she stands and breathes and feels she accepts that this is real, and in somewhen/someplace always will be, and she can live with that.

It takes two more days of visits before Martha feels she doesn't need to see that reality anymore.

Then she tries to find out what else she can see.

o0o o0o o0o

It's a world of disaster, not of destruction like the last, but humanity is struggling and every one of them knows the chips are down and the roulette wheel hasn't finished spinning, and the dealer's smirking in a way that has you pretty sure you won't be walking away happy from this one.

Depression clogs the air, and it reminds Martha of all the stories she heard about England during the Second World War, except that so many have finally given up fighting and there's no ally left to help them.

Martha is horrified by what she hears – refugees everywhere, rationing, concentration camps for former immigrants – it's like the war alright, but so much worse.

But she keeps her ears open and her brain alert, and some of what she hears and sees fits together with knowledge already in her brain, and she ends up in an army base being challenged by U.N.I.T. soldiers showing what seems to be an undue amount of suspicion.

And then the solemn blonde comes out, and the soldiers melt away like ice to water.

"Martha Jones," and her eyes are as assessing as they are sad, "according to everyone else, you're dead."

"Death is subjective," Martha retorts dryly. She should probably be shocked, or something, but at this point it's going to take a lot to shock her. "William Shakespeare's pretty dead, but go back four hundred years and I'm sure he's having a great time, probably chatting someone up."

The blonde woman simply looks at her, and there's a hint of warmth in the empty tundras of her eyes.

"What are you doing here?" she asks. Nothing else, no confusion or demands for explanations; and at that Martha suspects that she knows who this remarkable person is.

"You're the Doctor's Rose, aren't you?" There's no one else it could really be.

For a brief moment there's a smile on Rose's face, and it's real and like sunshine and the soldiers look astonished, but it's only there for a fleeting second before the solemnity is back.

" 'S s'posed to be a secret," Rose Tyler says, in tones of faint rebuke. "Come on. I'll show you something."

The something is a lonely dying TARDIS, and an arrangement of mirrors that makes such absolute sense that Martha stops dead, all the breath knocked out of her in surprise. Then she walks forward, slowly, and with a glance at Rose, who simply watches, walks into the centre of it. Rose orders the soldiers around, and they scurry to turn everything on, and Martha is suddenly bathed in bright light.

Martha looks into the mirror. As she half-expected, she isn't there. Instead, there's a little green ball of glowing energy, just hovering, harmlessly reflected back at her.

Martha stretches out her arm and wiggles her fingers, and maybe the ball's glow increases a bit.

Martha isn't surprised at all.

Suddenly, after all that hiding from herself, she's faced with the simple truth, and there's only quiet.

"Oh," Martha says, and although she says it softly in the near-silence everyone can hear. "I'm the Key."

And reality folds around her into a new reality and she's back where she came from.

o0o o0o o0o

Martha enjoys the rest of her leave from the hospital, spending the time with her family and catching up with all the friends who faded out of her life while she was having her existential crisis. She should be upset at being a little ball of phenomenonally-powerful green energy, but she's not. She remembers a lot more of the life she had before this, too, and it's a comfort rather than a burden. All the same, she's so very glad that the Doctor never looked too far into her past, and never worked out what she was: his people were terrible and great, and in the hands of a Time Lord the power of the Key could be used to shatter worlds.

She ends up joining U.N.I.T., and it's more interesting than she imagined, if a different way of life to what she's used to. She's human now, and that's who she is, and that's who she wants to be. There's a whole other side of her that exists outside of that, but it's the human part that matters. Life is dangerous and brilliant and sad and wonderful, and Martha loves all of it.

o0o o0o o0o

She feels a tug one day, a calling, and obediently folds around the world to fit herself into a new reality, and finds herself staring at three familiar faces, all older, all more lived in, but loved and recognised all the same.

They stare at her and Martha just stares back, not sure what to say to the people who were the foundation of Dawn Summers life.

"Well, this is kind of awkward," she manages. "I'm Martha Jones. I'm the Key."

And she gives them a smile full of life, that even on a different face should be more or less the same.

Willow doesn't look all that surprised – she knows of reincarnation, after all, and it can't be that bewildering that after being a girl so well, the Key would choose to make itself human once again – but Buffy and Xander look so lost and bewildered.

"You're happy?" Xander asks softly.

Martha nods, her eyes full of warm affection for the three of them.

Buffy and Xander and Willow look at each other.

"Then I guess that's all we need to know," Buffy says softly, and Willow ends the summoning and Martha lets this reality gently refold itself back into the one where she lives, and is happy.

END