Warnings: Prompt, character death.

Spoilers: Through episode 2.5.

Disclaimer: I don't own Fringe or its characters.

Author's Note: Written for Death Bingo on Dreamwidth, prompt: Man vs. Vehicle (train). With thanks to muselives and crazylittleelf for making sure this wasn't completely and utterly confusing to someone outside my head.

Mirror Darkly

The clouds flit back in front of the moon, rendering the abandoned train yard even darker. The figure Olivia has been following is gone. She grips her gun and concentrates, senses open to the slightest hint of where her target is hidden.

Not really reassuring, losing sight of the psychopath she's playing hide and seek with in the shadows of the rusted railcars. Not even when—or perhaps especially when—her target shares her face. Through a glass darkly, another Olivia from another universe where things went very, very differently.

She catches a flicker of movement from the corner of her eye. She turns, taking careful aim, but there's nothing. A footfall behind her, and she whirls and fires at a familiar shape that ducks behind the rusted hulk of a boxcar.

Her doppelganger's chuckle is chillingly familiar. "Not bad. Why're you still letting the FBI and Massive Dynamic pull your strings?"

"Because I'm not a psychopath."

"Can you really call me a psychopath when mostly I'm killing myself?"

~***~

Olivia darts backwards into the shadows, out of sight, listening for her other's footsteps. She's good, as good as any of the hers she's targeted.

Time to see just how good.

She reaches out, feels for the ebb and flow of the fabric of reality. Shifts through to a parallel world.

A quick scan of the area shows no major differences. The layout's the same, the rusted carcasses of trains are the same and in the same places. Night's a little clearer, not as many clouds playing peek-a-boo with the moon. She's been here before, already gone head to head with this version of herself.

A ripple cascades through realities and her other self steps through.

Adrenaline rushes through Olivia and she tightens her grip on her gun. Some of them never learned the trick to sidestepping realities, too caught up in Bell's exhortations of "can't be done" to open themselves to the possibilities. Some learned to sidestep, but were hopeless at tracking the movements of someone else. And some could do it all, but never learned to deal with the timeslips, making themselves easy targets to someone prepared to pick them off. This one, though, is as quick as any of them. Maybe quicker.

~***~

Olivia narrowly avoids a bullet fired moments after she followed her doppelganger into the new reality. A breathy laugh comes from the direction of the bullet.

"Not bad, Liv. Not bad at all. You've actually started to make use of your talent at this sort of thing. Become sure enough of yourself to start exploring your limits."

"Is that what you call this? 'Exploring your limits'?"

"I call this my personal crusade."

"Who do you work for?"

"Myself. C'mon, Liv. What did the FBI ever do for you, really? In the end, all they're good for is killing everyone you ever loved. And Massive Dynamic is even worse."

Unease curls through Olivia's belly. Distraction or truth? "What do you mean?"

"Trying to keep me talking, Agent Dunham? Too scared to just look in the mirror, so you're using all those hours of studying the worst that humanity has to offer to figure out what makes me tick? Here's a bit of information for your profile: You don't kill me tonight, I'm going to keep coming after you."

Reality ripples and her doppelganger disappears again. Olivia braces herself and grabs at the ripples, running as she pulls herself through to the other side. She hits the ground and rolls, narrowly avoiding another bullet.

"You'll have to do better than that," her doppelganger taunts.

If Olivia doesn't take control of the situation, she's dead. Her doppelganger is focused on taking her out and won't stop until she accomplishes the task. Olivia knows herself, even as twisted as the self she's facing is.

She won't stop.

Olivia bares her teeth in a feral grin and feels for the weakness between realities. "You want me? Come and get me."

And she steps through the barrier into another world.

~***~

"That bitch," Olivia breathes. This is the first her who has taken the initiative. This one is different. More advanced. Maybe she could even handle the truth.

Olivia considers opening the lines of communication. This one might be convinced, if she's seen enough. The thought is discarded quickly. Death is the only possible solution. They all need to be dead.

Olivia keeps a hold of the reality she needs to find, circles the place where her other self disappeared. She shifts realities at a run, comes through with all her senses attuned to the new world around her, and still misses the whine of the bullet until it clips her shoulder.

She flings herself to cover before the second bullet, crouches and reaches for her shoulder once she's sure she's hidden. Just winged her, really, but the burn tugs at her arm with every movement. She's never been wounded by one of her targets.

Is she getting careless, or is this one really that good? That good, her instincts say, and she hopes pride isn't overriding common sense.

Good enough to turn the tables, she decides after exchanging a few rounds while dodging between rusting hulks of boxcars. Olivia's no longer leading her other self on a merry chase but periodically trading off the lead. She's pretty sure one of her shots connected, but her shoulder burns even more, blood soaking her sweatshirt. Should have stopped bleeding by now, but there's still blood trickling down her arm. The bullet had more than winged her.

She shifts realities, this time hoping for a moment to recover her breath.

~***~

Her hip hurts. The wound's not lethal but it slows her down, pain dogging every step, and it's still bleeding sluggishly. Olivia leans back against the railcar and tries to slow her breathing, wondering who's on the run from whom now.

Her skin prickles, and she can feel her doppelganger prepare to move. Olivia reaches out, feels where the doppelganger is going, and lets the rippling opening between worlds slingshot her there first. Her shot hits more solidly this time, and her doppelganger clutches her right shoulder, eyes wide, gun dropping forgotten to the ground. Olivia aims between the eyes, determined to finish this.

And hears the click of a gun empty of bullets. Cursing, she starts to reload, and her doppelganger sprints behind cover.

But she left her gun behind with the pool of blood.

Doesn't mean she's unarmed. She should have her holdout gun strapped to her ankle, maybe another if she's come prepared.

Olivia hears her doppelganger's shallow pants, can imagine the pain she must be in. "Come out and end this," Olivia calls out, circling to find a spot where she can see her target but not be seen.

"That's what I'm trying to do," her doppelganger snarls. "They'll use us to destroy everything."

"Who?"

"Massive Dynamic." Her doppelganger says the name with a level of hatred and loathing that borders on madness.

Olivia shudders at the tone, wondering exactly what could have triggered that murderous rage. "I'm not letting them use me," she says.

"You just don't know yet." Her doppelganger's voice is bleak. "I didn't think it. Doesn't matter what world we're in, they're all the same. I'm not leaving good old Massive Dynamic anybody they can use. I promised I'd stop it. I promised."

The yard is still echoing with her doppelganger's words when she sidesteps into another reality.

~***~

Olivia nearly blacks out from the effort it takes to shift realities so quickly, but she grits her teeth and perseveres. And then she does it again, and again. If she goes fast enough, for long enough, she can dodge her tail. She'll heal up, come back later.

Her other self will be ready, prepared for the attack, but it has to be done. Killing her, all of her, is the only way to stop Massive Dynamic from destroying her universe. From destroying all of the universes. Peter had said that Olivia was the key. They'd tried to stop him from telling her, but they'd been too late. Holding his cooling body as she watched Walter and Astrid staring sightlessly across the lab in matching and mingling pools of blood had only burned that knowledge deeper. The key has to be destroyed before Massive Dynamic can rip the fabric of reality apart.

She promised to stop the destruction any way she could. She holds to that promise, and pushes herself to run faster and farther. There's no shame in running away to recover, not when she knows she'll come back to finish the job.

~***~

Olivia's head throbs in time with the scatters of starbursts that dance behind her eyelids. Her doppelganger keeps shifting realities, already starting to disappear before Olivia has arrived, almost faster than she can keep up. Only almost, because she's pushing herself to follow, paying no attention to anything except where her target has gone next. She's gaining, with each shift adding seconds to the time they share the same reality. Not enough to get off a shot, not yet.

It's almost too late when she registers the bright lights and throws herself backwards, feeling the rush of the train. Her doppelganger isn't as lucky, tossed twenty feet to hit a nearby box car, then slipping to the ground with a thud. She lays there, unmoving, sprawled like a broken doll. The train whizzes by without stopping.

Olivia hugs the ground and watches the train, heart thumping as she realizes how narrow her escape had been. When the train has passed, she pushes to her feet, scanning the very much still in use train yard with wary eyes, and cautiously limps towards her doppelganger.

Blood trickles out of her mouth and her eyes are glazed with pain. She fumbles in her pocket. Olivia backs up and aims her gun, but it's not a weapon in the other woman's hand. She clutches a USB drive, and waves Olivia closer.

Olivia kneels by her doppelganger, and the woman presses the drive into her hand. "Stop them, 'Livia," she whispers. "Don't let Peter and Walter and all the rest have died in vain. Please. It has to have been worth it. Please let it have been worth it..." And her eyes go blank and her body limp.

Stopping her doppelganger isn't as satisfying as Olivia had expected. Not as satisfying at all.

Olivia gathers herself in her arms and feels for the familiar tug of home. Pulls both of herselves there on the last dregs of her strength, back to that abandoned train yard full of relics of a past day. The headache all but blinding her and her consciousness fading in and out, she pulls out her cell phone and dials. She needs help, and fast, and there's only one person she trusts since everything became so fucked up. "John," she whispers when her husband finally picks up. "I need you."