A/N: An AU Naoto-in-Secret-Base fic. One of the earliest stories I wrote and it shows. But, tried to clean it up. Many thanks to Rayless Night for her previous crits on this.

(For a more recent, in-universe version of Naoto-in-Secret-Base, check out 'Interlude 2' in my other story, 'The Shortest Distance from A to B')

The bitter chemical tang in the air is the first thing Naoto notices, even before the cold against her back and wrists. Not the same sticky sweet chloroform she remembers from earlier; this is sharp and burns her throat.

"Don't fight it, Naoto-kun."

It's her own voice, but the deeper one - the one she's practiced for years and never quite mastered. A figure slowly blurs into her vision, leaning over her as she gazes at the ceiling.

"We're going to make things better, you'll see, so, so much better."

Her vision sharpens. The smudged face resolves itself into hers - but the eyes are less wide, the lips thinner, the jawline stronger.

It's how she should look.

It is also completely impossible. Naoto's judgments are grounded in science, and no technology exists that could create such a duplicate. The doppelganger - a mere illusion, she decides, smoke and mirrors - reaches down to cradle her head, coat sleeve sliding down his arm, fingernails digging into her scalp.

"I have to fix you, Naoto," he spits. "You're useless as you are."

Throat too dry to talk, Naoto settles for a dull glare. Things that aren't broken don't need to be fixed.

"You understand, yes?" The Shadow's expression softens. As he turns and moves out of her vision Naoto tilts her head to follow, cheek pressing against the metal table.

Without warning, he stops a few feet away and pivots in place. He stares at Naoto, arms wrapped around his body, eyes far too wide, before he - she? - screws them shut.

"I have to fix you," the clone says again in a voice that makes Naoto's stomach twist, rocking on her heels and tugging at the sleeves of her over-sized lab coat.

When Naoto next awakes, still dizzy, the clone is adjusting a mechanism above her head. Again her throat scratches with the effort of speaking, but she manages to choke out a protest. "What are you-"

"Silence!" he snaps. "Do not hinder my preparations. Fixing you is by no means a trivial procedure."

This creature isn't her. Naoto is certain of that, and not only for the obvious reasons. His eyes are colder, his movements staccato and erratic. She thinks back to Port island, the nightclub, and Amagi's inane babble about Shadows; in retrospect, possibly the one moment of honesty Seta's group displayed.

The realization is bitter on her tongue. Naoto swallows hard. "Changing me?"

"Are you truly so stupid? Ruminate a little more, Naoto-kun." The Shadow jabs a finger against her ribs. "How long have you tolerated this fragile shell?"

The metal shackles are tight around her wrists. She has no hope of breaking them. But she might, if things were different.

"You converse as an adult, attire yourself as a male. You delude yourself on a daily basis."

Naoto jerks her wrists forward on instinct - he's wrong, he doesn't see- then stiffens. Throwing a tantrum over this pathetic clone would make her equally pitiable. "And you - you betray your utter lack of insight. Your reasoning is flawed, because - because -"

The Shadow tips his head. "Because?"

Naoto doesn't answer; for once, has no idea how. The Shadow stares at her, struggling against the shackles, and no one else she's ever heard laughs with such emptiness.

Later the Shadow sits on the table beside her, twirling strands of Naoto's hair around her fingers. "It won't be so bad. You won't have to pretend anymore."

Naoto's gaze remains fixed on the machinery above the table. "I do not pretend at-"

"We're very good at it," the Shadow interrupts, leaning over her, trailing his fingers down her face. "We almost fool people. Maybe even ourself. But it won't last." His lips twist into a smirk. "You can be a boy, counterfeit prince, but you will never be a man."

Ironic, Naoto thinks. Being an adult - the thing she craves most in the world - makes the illusion impossible.

"If you are an adult, they will consider you valuable. If you are a man, they will listen." The Shadow scrapes his fingernails along her cheek. "And desperation hurts, doesn't it?"

Of course it doesn't. And she would hardly know.

Naoto bites her lip.

"But you cannot have both. Not without my help." He pulls his feet onto the table and starts to rock back and forth. "You need me. I know how to do it. I know lots of things."

"Then release me."

"Like how lasers work. And how to put them in pistols." The Shadow points at a table standing against the far wall of the room. "I already did it. Do you want to see? I did it."

"...Yes. If you unlock my restraints."

The Shadow narrows her eyes - as Naoto holds her breath - then taps one lab-coat covered hand idly against her shoe. "You won't leave? You promise?"

"I promise," Naoto lies.

The Shadow grins.

Naoto doesn't leave - at least not immediately. After all, she has to wait for the self-styled investigation teamto arrive. Ludicrous. Children playing at heroes.

"Much like ourself, yes?" The clone smirks at her from the metal floor, though she doesn't recall speaking aloud.

She rolls her eyes and turns back to the computer monitor. The screen displays footage from ten cameras installed around the laboratory's interior: one over the workbench, another beside the main door, yet another hanging high above the operating table. Combined they observe every corner of the room, yet Naoto has seen no-one save her clone since first awakening.

No other inhabitants, no visitors, and the doors are kept locked tight - leaving an elaborate security system which tracks nothing at all.

"This makes no sense," Naoto says. "We are the only two people here."

"One person," her Shadow points out.

Naoto ignores her. "The cameras are purposeless."

The Shadow flops over onto her stomach, chews at her thumbnail for a moment, then looks up. "Do flashing detective badges have a purpose? Or knife-shaped radios?"

Naoto pauses.

"Of course not," the Shadow answers for her. "But we've always enjoyed this sort of thing, haven't we?"

The conversation is as pointless as the cameras. Naoto turns away from the screen.

Time passes slowly. Naoto has investigated the machines, the monitors, the endless trivial toys the Shadow insists on showing her. Now she spends much of her time wondering why Seta's group still hasn't arrived, and how much longer she has left.

"You aren't interested," her Shadow whines, after demonstrating the spring-loaded lock-pick wristwatch for the third time.

Naoto folds her arms with a sigh - then cringes as the Shadow starts to sniffle.

This, too, is horribly familiar.

"It's not fair. Why doesn't anyone pay attention?" The Shadow rubs her eyes with the lab coat's over-sized sleeves. "It's not fair!"

"Grow up," Naoto snaps. "Do you honestly expect to win approval through such juvenile actions?"

When the Shadow drops his arms, his face is twisted into a sneer. "But isn't that your own approach?" He moves closer, closer - until he's only inches away and his hands snap over her shoulders. "Allowing - no, encouraging your own kidnapping, all to prove a point? To prove your worth?"

"That - that wasn't it," she insists, staring into narrowed yellow eyes. "It was to solve the case."

She does not require anyone's approval. She never has. Not like this...this child, this pathetic creature hiding in a lab and building trivialities.

The Shadow rumbles with laughter, shaking her in turn. "Tell yourself what you wish, Naoto-kun."

I could leave now, Naoto thinks, and tries to believe it's true.

After all, she's already proved Kubo's not the killer, and the noises outside aren't monsters, despite what her Shadow insists while huddled sobbing under a desk. No such thing. And any place with an entrance also has an exit.

Simple.

I could leave now.

"But then who would ever believe you, little prince?" says the Shadow.

The Shadow watches carefully from the floor of the lab, coat pooled around her legs with her fingers tangled in the sleeves. "Do you want to play something?"

Naoto stares at her. "What do you-"

"We could play a game." The Shadow tips her head to one side. "Do you know any?"

Games are simply idle distractions - but that seems too alien a concept for the Shadow, this child who builds robots and clutches at Naoto's arm when the noises outside grow too loud. "Don't be ridiculous."

The Shadow thumps her heels petulantly against the steel floor. "You just don't know. No wonder the policemen didn't like you. You don't know anything."

Naoto clenches her jaw, grinding her teeth. A full minute passes before she's calm enough to notice.

They'll come for her soon. They need her. She's a detective; more than that, she's a Shirogane. Without her, they'd have stopped at Kubo.

I can help them, Naoto thinks.

Somehow, the Shadow hears. He sneers at her from across the room. "Imbeciles, Naoto. We surpass them all. A fact you've known since meeting them. There's no place for you there."

Her mouth is dry, her Shadow is a fool, and Naoto chooses not to listen. "You're lying. They'll want my assistance."

The Shadow's lips curl into a smirk. "Why? What use is a flawed and lonely child?"

The words sting like a slap to the face and Naoto's skin tingles with heat - but the Shadow still speaks the truth.

And if the Shadow's correct, then the team will never come. Which is fine. Naoto has years of self-reliance to count on and she is perfectly capable of escaping on her own. Unfortunately, the lab has only a single exit and the control panel to open it is locked tight.

In a laboratory full of rayguns, drills and corrosive chemicals, she chooses the simple approach. Her Shadow left the lockpick wristwatch on a workbench as soon as her attention drifted elsewhere. Standing in front of the control panel, Naoto's concentrating so intently on the final, most troublesome pin of the five that the burst of pain in the back of her head is entirely unexpected.

"Pathetic! Given all the tools, all the equipment, and you remain unable even to open a door!"

Naoto barely registers the words between the flashes of light behind her eyes and the ringing in her ears. A wrench clatters to the floor beside her head, and a foot - in a blue-black platform shoe, of course - kicks her in the side, tipping her onto her back.

There are tears rolling down the Shadow's face, even as he - she? It's becoming impossible to tell - rants and raves. "You're so, so stupid, you lied, you said you'd wouldn't leave!"

True enough, Naoto thinks with a small and inexplicable pang of guilt, just before she passes out.

Naoto's eyes flicker open. Next to her, the Shadow lies curled up on the floor with her arms round her head. Her hat - a perfect replica of Naoto's own - lies a few inches away.

"You c-can't leave, you can't!" She draws her knees up to her chest, disappearing into the folds of the lab coat. "But you tried, you were going to go!"

There's no logical reason why Naoto should feel guilty. She bears no obligation to a faulty clone.

"Everyone always leaves. I'm always left alone, and I, I-" The rest of the sentence dissolves into sobs.

A lonely child. Nothing more, Naoto thinks, and sighs.

When she reaches out to touch her Shadow's arm, cold fingers snap around her wrist. "Promise me you'll stay."

Trying to shake her head is a mistake, judging by the sudden rush of pain and nausea. "I'd...I'd be lying."

The sobs abruptly stop. "You ought to be accustomed to that," the Shadow says with a sharp and twisted smile, squeezing Naoto's fingers so tightly she thinks they might snap - except that thinking at all is a challenge. Her vision is swimming, and Seta's team (who'll never accept her, she knows that now) still haven't arrived.

They were dishonest with her, but she was equally dishonest with them.

She takes a shuddering breath; tastes chemicals and motor oil. "I-I know."

On the floor beside her, the Shadow stares at Naoto with an expression she can't recall seeing before - then drops her hand and curls up at her side. She tries to mold herself to Naoto's form, dipping her head down and tucking it in the crook between Naoto's shoulder and neck.

"They're not coming," she whispers.

The Shadow is right. Desperation granted Naoto both entirely too much faith in their abilities, and the delusion that they would ever care.

The ceiling is spinning enough to make her sick. She screws her eyes shut.

"And if they don't," and Naoto feels the Shadow burrow deeper against her neck, "you'll stay, right? Please?"

Naoto doesn't answer - just tangles her fingers in an identical mop of dark hair. The Shadow grabs her hand in response and locks their fingers together, mirrored and overlapping.

"We don't need them anyway." The Shadow's lips are as cold as the metal floor. "It's always been just us."