AUTHOR'S NOTES:

Hey there, folks! Thanks for joining me for another chapter. Hope you enjoy!

CHAPTER NINETEEN | LAB RAT

It was late afternoon when they arrived in Radiant Garden. They alighted outside the castle doors in the same forecourt as their last visit. Kairi found herself drifting towards the wall again, drawn by that same sense of familiarity. Her gaze settled on the small cottage on the horizon, filling her with a sense of loss and longing that left her confused (amongst other things). Kairi knew how to get to it – she would need to go through the royal gardens, across the small stream that ran down from the courtyard, and then she would need to take a winding cobblestone path that would lead right up to the front door – but she didn't know why she knew.

"Kairi? You coming?" Axel asked. She turned away from the fields; it was a mystery for another time. Instead she nodded and smiled at the others who were waiting patiently by the doors. Dilan and Aeleus both nodded to her as she passed (and scowled at Axel, who stuck out his tongue in return). Kairi's heart skipped a beat as they passed through the large doors and she stumbled mid-step; Axel glanced at her out of the corner of his eye and she smiled.

"Caught my toe," she mumbled sheepishly. He frowned but didn't ask about it further.

The last time she'd been inside the castle it had still been under Maleficent's control and it had been flooded with a sickening darkness that had made her stomach roil. The darkness was gone now, but the knot in her stomach was tighter than ever as they turned down a series of narrow corridors lined with copper pipes. The blue checkerboard carpet made her heart leap to her throat, though when she reached out with her senses she couldn't figure out why.

Eventually the red and purple walls gave way to a pleasant cream that surrounded an ornate wooden door. Kairi froze at the sight of it.

"Kairi?" Riku asked. "Are you all right?" She stared at him, feeling her heart racing.

"I…" What could she tell him? Something wasn't right, and yet nothing felt wrong. There was no darkness, no malicious evil waiting for them that she could sense beyond the door. There was just Ansem's study, his computer room and, beyond that, his laboratory. Ansem was there with Even and Ienzo, and she was here with Axel and Riku and Mickey. Even if something was waiting for them, she was in good company. She shook herself and smiled. "I'm fine." All three of them stared, watching her carefully, and when they showed no signs of relenting she added: "It's just Vanitas. We were talking about vessels." Not the most convincing lie, perhaps, but it seemed to console the others enough that they pressed on.

Don't involve me in your lies, Vanitas huffed.

I'm sorry, she said. I didn't know what else to tell them. I don't know what's wrong with me.

You're scared of something, he answered. Terrified. It's written plain as day on your heart, but I can't figure out what you're scared of.

Neither can I.

The fear didn't relent as they stepped in to the office. It was large and round, with curved bookshelves lining the walls filled with crimson tomes. On the desk were stacks of paper and piles of books, and on the wall behind the red velvet chair a painting of the castle had been hung in a beautiful golden frame that sparkled in the light. The fear persisted. Her eyes tracked Riku as he approached a blank section of wall between two bookshelves. He pressed his hand against it and, after a moment, it flashed and disappeared to reveal a hidden corridor beyond.

Kairi's stomach twisted. Her heart leapt to her throat and she swallowed bile as she stumbled backwards.

"Kairi?" Axel called. "What is it? What's wrong?"

"I… I…" Her eyes were fixed on the doorway and her feet were glued to the floor. Her breath was coming in short gulps and her head was spinning.

"Kairi?" Riku was at her other side now. The flash of his silver hair turned her blood to ice and she stumbled backwards. Her hip collided with the desk and she clutched at it tightly, closing her eyes. The world was spinning. Hear heart was racing. She couldn't breathe.

"Axel, get her out of here!" she heard Riku order. Strong arms scooped her up from the floor and soon she was flying.

Kairi, snap out of it! Vanitas' roar was muffled by the pounding of her heart in her ears. She clutched at Axel's shirt, gulping for breath.

"It's gonna be all right, Kairi," Axel soothed. "You're gonna be all right." She tried to focus on the pounding of his footsteps but they sounded so far away. She felt like she was falling. Drowning. She clutched to Axel tightly, like he was driftwood in a storm, keeping herself afloat.

"Is everything all right?" a deep voice asked. Kairi's stomach twisted at the sound and she gasped for air that didn't reach her lungs.

"I don't know," she heard Axel mumble. Something heavy scraped against stone and she was placed in a large chair. She pressed herself in to it, curling up in to a tight ball against the plush armrest and pressing her face in to her knees. The conversation continued around her but it was muffled and fuzzy – like she was underwater. Someone took her hand.

"Kairi, it's Aerith." The voice was soft and gentle. "I brought you some water. Careful, you don't want to spill it." She pressed the glass in to Kairi's trembling hand. It sloshed over her fingers and Kairi opened her eyes, watching as the water ran over her skin. It was ice cold. She clung to the sensation, to the exclusion of all else; focusing every ounce of concentration on the feel of the water and the chill it left behind. She took a deep breath – one that finally reached her lungs and stuck. She watched the glass, careful not to spill any more water. Slowly the room stopped spinning. The world came back in to focus. Finally the glass stopped shaking and Kairi pulled her eyes away to find Aerith kneeling nearby, a kind smile on her face. Over her shoulder, Axel stood beside Dilan, both of whom were watching her with no small amount of concern.

"Have some water, Kairi," Aerith urged gently. Kairi uncurled slightly and sipped at the water. It was so cold it made her teeth hurt. She took another sip. The ache in her jaw was at least a temporary distraction from the pain in her chest. She sought out Axel, and when their eyes met he flew to her side.

"What… What was that?" she asked.

"I'm not sure," Axel answered, brushing strands of hair from her face. "Are you all right?"

"I don't know." Her hand trembled again and she took a deep, steeling breath. "There's something down there, Axel. Something I… I don't remember." Footsteps were approaching. Kairi took another sip of water to ease the knot in her stomach as Riku rounded the chair and crouched low beside her, his eyes searching her face.

"Kairi, are you all right?" he asked. She nodded slowly, taking another sip. She watched Aerith as she stood and took a step back to give them room. Kairi's eyes landed on Mickey then as he emerged from the corridor, followed closely by Ansem the Wise. His expression was one of sorrow and pity and he stared at her, and she felt herself shrink under his gaze.

"I had hoped that you would not remember," he said solemnly. Mickey tilted his head upwards.

"Remember what?" he asked. Ansem closed his eyes and folded his hands behind his back with a deep frown.

"As you know," he began, "after Xehanort gained control of Terra he became my apprentice. I fear that it was my research that provided him with the inspiration for his own… investigations. It certainly provided the tools he needed to pursue his derivative experiments." His eyes opened, and his piercing golden gaze left her frozen in her chair.

"What kind of experiments?" Axel growled. Flames danced along his fingertips and he clenched his hands in to fists to keep them from spreading. Ansem stared at her a moment longer before turning his attention to Axel.

"He became obsessed with finding a keybearer," Ansem answered. "He discovered a theory that the heart of a keybearer could create a resonance with a heart of pure light."

"The Princesses of Heart," Mickey murmured.

"Just so. At the time he was unable to leave this world, and so his access to pure hearts was limited. He determined that children had a higher probability of having a pure heart, and he became obsessed with releasing those hearts to track the resonance and follow the path to a keybearer."

"What kind of experiments?" Axel repeated. Ansem sighed.

"I do not know the exact details," Ansem answered heavily, "but I know that they involved submerging the subject in darkness. Kairi was one of the more fortunate test subjects." Riku shot to his feet with a furious glare.

"Fortunate?" Riku demanded. "How is this fortunate?"

"Most of Xehanort's experiments perished in the darkness. Those who were strong of heart became heartless themselves, and we have no way of knowing if they were ever able to regain their physical form. Kairi is the only subject I know of who survived the experiment unchanged. Doubtless your survival was due in no small part to the spell Aqua cast upon you." Kairi's fingers found the pendant around her neck and she clutched it tightly.

"How many others were there?" she asked. Ansem's expression fell, overcome by sorrow as he turned his attention back to her.

"More than I could bear," he answered. "By the time I realised the extent of what he was doing, I was too late. I managed to save one child – a girl with no memories and no name – but she too disappeared." Axel sat up taller and the flames at his fingertips disappeared in wisps of smoke.

"The girl from the dungeons?" he asked. Ansem nodded and Axel's eyes narrowed dangerously. "You took her away?"

"I attempted to save her from her fate," he answered. "At the time I had no way of knowing that Kairi had survived. I thought that she had met the same end as the other subjects, and I blamed myself for not putting an end to Xehanort's research sooner."

"What about the girl? What happened to her?" Axel asked.

"That, I cannot tell you. My attempts to keep her safe were for naught. I can only hope that she managed to somehow flee to safety. I do not blame her for wanting to run from me. My pursuit of knowledge turned me in to a dangerous man. No doubt she did not feel safe, even when I went to great lengths to try and keep her hidden away." Axel's face fell and his shoulders slumped.

"I'll have to tell Isa," he murmured.

"Kairi," Ansem continued. She jumped at the sound of her name; the last of the water spilled in to her lap. "Mickey tells me that you have come in search of a vessel for Vanitas who has taken up residence inside your heart." Kairi's voice had deserted her and she could only nod.

"He saved her life," Riku said when she remained silent. "In return, he asked that Kairi secure a vessel for him."

"Are you sure this is wise?" Ansem challenged. "Not too long ago Vanitas would have handed you over to the enemy in a heartbeat. How can we trust that he has truly changed for he better?"

"Kairi trusts him, as does Sora," Riku said firmly, "and so do I." Mickey turned to Riku, eyes wide with surprise, but Ansem remained unmoved. He frowned deeply.

"If we are wrong-"

"We're not," Riku countered. "He didn't have to save Kairi's life, but he did. I don't think he would turn on us, but even if he did we're more than strong enough to contain him."

"He promised to fight for Sora," Mickey added, though with somewhat less conviction. "After our last clash with Luxu and the other Apprentices, we could use all the help we can get." Ansem stared at them each in turn before finally nodding.

"It will take a few days, but we can create a vessel for Vanitas." He paused and glanced to Kairi again. "When the time comes, you will need to enter the laboratory to transfer Vanitas' heart in to the vessel." Kairi's stomach tightened painfully.

"I understand," she said, though her voice wasn't quite as convincing as she'd hoped it would be. Nevertheless Ansem nodded.

"I cannot promise to make you comfortable in the laboratory, but I can promise that all of Xehanort's equipment has long-since been destroyed." He seemed to study her for a moment before adding: "No harm will come to you." Axel slowly rose to his feet.

"You'd better not be making promises you can't keep, old man," he growled.

"The process of extracting Vanitas' heart may cause some discomfort, but I do not expect there to be any pain," he answered. "We will make the process as comfortable as possible, and the rest will be up to Kairi." The thought made her shiver. She glanced towards the narrow hall and swallowed bile. She didn't want to go back there, but Vanitas… He was counting on her. She swallowed thickly and nodded. Aerith reached over to take the empty glass from her hand.

"Why don't we take you down to Merlin's?" she suggested. "I know Yuffie will be happy to see you."

"An excellent idea," Ansem agreed. "There is nothing more that you can do here until the vessel is ready. We will call you when it is done." Kairi nodded and slowly peeled herself out of the chair. Axel offered her his hand to pull her to her feet, though he refused to let go even after she was standing. His hand was warm and comforting and grounding, and it kept the world from spinning as she quietly followed the others back out in to the early evening.

By the time they emerged back in to the forecourt the sun had begun to set, casting a golden haze across the castle and the flower fields. Kairi glanced out towards the cottage again. There were lights coming from inside and lazy wisps of smoke had begun to rise from the chimney. Kairi wanted to run to it, but she couldn't figure out why it felt like safety. Besides, it was late; no doubt whoever lived in that cottage wouldn't want to welcome unexpected visitors at this hour. And so she followed the others in silence, still clinging to Axel's hand as they made their way out of the castle grounds towards Merlin's house.

She couldn't sleep.

The others had been waiting for them when they'd arrived. Yuffie had been her usual excitable self, and had bounced over to Kairi to give her a tight hug and express how relieved she was that Kairi was back. Leon's stoicism seemed to have melted somewhat since Kairi had last seen him; he seemed less bothered by Yuffie's boundless energy, and while Yuffie and Aerith were making tea he had sat next to Kairi and quietly asked how she was feeling.

She'd been saved the trouble of answering by the arrival of Merlin who had appeared with his usual chaotic flair. The smoke had made her throat itch. He had greeted Kairi warmly, holding her hands tightly and expressing more in a single, sad smile than words could ever say, and when Yuffie handed Kairi a mug of tea he had waved his fingers over it, imbuing it with calming magic. It had settled her frayed nerves long enough for her to eat a small dinner. The lingering terror from the afternoon faded as they ate, and by the time Yuffie and Riku cleared away the plates she found herself exhausted. She spent several hours in one of Merlin's absurdly tall armchairs dozing in front of the fire while conversations continued around her until Merlin announced that the spare rooms were ready.

The room that Merlin had given her was small but cozy. It reminded her of her old bedroom back on the islands – nice and snug with a small set of draws, a wardrobe, a small desk and a cozy bed piled high with pillows and blankets. She had buried herself beneath them and curled in to a tight ball, but as soon as she'd closed her eyes she was haunted by visions of long white coats, silver hair, and heartless pressing at her from all sides.

Merlin had left her a teapot of calming tea, enchanted to stay warm throughout the night. After hours of tossing and turning, drifting in and out of waking nightmares, Kairi finally gave up. She took the softest blanket she could find, wrapped it around her shoulders and poured the tea in to a large mug. She pulled back the heavy curtains and curled up on the windowsill, gazing over the sleeping city below. For a while she was calm again, watching the stars and the flickering streetlamps, but all to soon the tea ran out and its calming effects began to fade, and Kairi was left curled in the corner of the window staring up at the castle.

Let me help you. Vanitas' voice made her jump. She leaned her head against the cool glass, feeling the sharpness of the cold pane against her skin.

You can't, she thought back. You can't change the past.

She'd come to Radiant Garden to escape – to try and find some peace and, perhaps, some of her missing memories. She'd expected it to take days of exploring, of asking around, of reaching out to see if anyone knew her or knew where she'd come from. She hadn't expected her past to slap her in the face within minutes of arriving, and she certainly hadn't expected it to feel so… so…

She didn't know what she was feeling. Everything was so messy; a tumult of emotions all warring with each other for her attention until she couldn't tell one from the other. She was too exhausted to try and untangle them all. And even if she could, what then? It wouldn't make her feel any better.

Because sitting here wallowing is such a helpful choice right now, Vanitas huffed.

You wouldn't understand-

What it's like to be experimented on against your will? he asked. Yeah, you're right, I've got no idea what that's like. She sighed and rolled the cold mug between her palms.

I'm sorry, Vanitas, she thought. I just… I don't know what to do… I don't even know what's been done to me in the first place.

Well you won't solve anything if you can't control your emotions first, he countered. I can help with that.

How?

The shadows shifted at her feet and sprang to life. The unversed cowered at the far end of the windowsill, watching her with its beady red eyes before it darted away, zigzagging across the room until it could cower by the door. It's jagged antenna twitched.

Destroy it, Vanitas ordered. Kairi drew the blankets tighter around her shoulder.

I won't. It doesn't deserve to suffer just because I'm upset.

Suffer? Vanitas scoffed. This isn't living creature or even a heartless. It's made from your fear, it's just an emotion.

Kairi watched the unversed carefully. Its beady eyes were darting around the room as it shifted its weight back and forth, never staying still. It rubbed its pointed forelegs together nervously, and whenever it caught Kairi's eye it shrank back in fear. It certainly looked alive.

It can't think, it can't feel, Vanitas hissed. It's nothing but emotion – your emotion. If you don't destroy it now then you're weaker than your fear, and we both know that's not true.

She gnawed the inside of her cheek. What harm could it do, really, to prove to herself that she was stronger than her emotions? That she was in control? Her hand emerged from beneath the blanket and before she could stop herself she had pierced the unversed with a shard of ice. It was rigid for a moment before dissolving back in to the shadows with a sigh. Kairi felt a dull ache in her chest.

That didn't help, she sniffed.

Of course it didn't, it was only one, Vanitas snapped. Several more shadows appeared, skittering this way and that around the room. Try again. Kairi sat up taller and placed the mug down, freeing both of her hands. They were only emotions, she reminded herself. Her emotions, and she was stronger than them. This time she summoned light and she fired tiny bursts of it at each of the unversed. One by one they disappeared, and with each one she felt a pang in her chest. By the time she had defeated them all she couldn't deny that her head felt at least a little clearer, though what little clarity she found was soon lost behind more warring emotions.

I'm not fast enough, she sighed.

No, Vanitas countered harshly, the unversed aren't big enough. You need to get outside.

Outside?

Unless you want to tear this room apart, he drawled.

I can't leave. Someone will notice!

So sneak out, he shot back curtly. There's a window right here.

I can't climb down!

Do you want my help or not? he snapped. She bit her tongue; it was less a case of want and more a need. If she could just clear her head then maybe she could think straight, and seeing how she'd failed to do so on her own…

She sighed and stood, throwing the blanket back on to the bed. The night air was cold as she stripped out of her pyjamas and in to a pair of long shorts and a loose over shirt. Carefully she opened the large panelled window which swung out in to the night like a door. She perched on the outer sill, gripping the frame tightly with one hand as the other summoned her keyblade. She threw it high to transform it to her glider, and after making sure the window couldn't close all the way and lock her out she shot in to the sky.

They landed in in the flower fields below the castle. Vanitas gave her a moment to dismount, but as soon as her keyblade was in her hand the unversed were springing from the shadows. Kairi took a deep shuddering breath and swung for the nearest creature, slicing it clean in half. Then she found another, and then another, and before she knew it she was cutting down the unversed faster than they could form. Within minutes her fear had begun to dissipate.

Vanitas didn't relent. The next unversed he summoned was much larger, with a toad-like body encase in a spiked shell. Two thick, striped whiskers sprouted from either side of the creature's face ending in sickly pink spiked slabs that knocked Kairi clean off her feet when she wasn't looking. It took in a deep gulping breath and its belly tripled in size before it launched itself in to the air. It stomped towards her, creating a shockwave of power that sent her stumbling backwards.

"Vanitas!" she gasped, catching her breath and blocking its next attack as it rushed past her.

It's your anger, not mine, he retorted. The unversed turned slowly towards her, its narrowed eyes watching her closely. She planted her feet and lowered her keyblade, waiting for it to charge. This time she was ready; the whiskers whipped back and forth in a fury as it barrelled towards her and she blocked them with her shield before launching an attack at its face. Its eyes, situated on two dark stalks, flared dangerously with each successful blow.

"Light!" Pearls of light sprouted from the tip of her keyblade to encircle the creature where they lanced down to spear it. The beams above its armoured shell were deflected, but those over its head and legs struck true and the unversed disappeared in to smoke and shadow.

Vanitas had been right; this was helping. Fighting gave her a way to release the pent up energy that had been pooling in her limbs, and with each unversed she defeated her heart felt lighter and her head felt clearer. Finally, as the darkness of night began to give way to the pre-dawn light, Kairi dismissed her keyblade and wiped the sweat from her brow.

You're not done yet, Vanitas scolded. Summon your keyblade.

"I'm done for now," she answered. She took a deep breath of the cool morning air and closed her eyes, feeling the breeze dance across her sweat-soaked skin. The chill made her shiver.

You're done when I say you're done, Vanitas snapped. She collapsed in to the grass and opened her eyes, glancing around the field. Swathes of flowers stood wilted, broken or outright trampled. Kairi winced and glanced up to the castle; surely somebody would notice the destruction. Would they raise an alarm?

Stand up, Vanitas ordered.

"We need to get back," she answered. "If someone notices I'm missing, it'll cause chaos."

You're not finished, Vanitas said curtly. You've barely scratched the surface of your emotions, and you're still not in control.

"I'm in control enough," she said. She rolled her neck, wincing at the knot that had formed between her shoulder blades. She wondered if she would have time to shower before anyone else got up. She wondered where the shower was.

A shadow shivered at her feet. A little unversed – a flood, Vanitas had called it – was standing near her toes. This one was sitting back on its haunches, its forelimbs stuck in the ground as though ready to pounce. This one was angry.

Get up, Vanitas hissed. Kairi frowned.

You can't expect me to master my emotions in one night.

I did.

Well, I'm not you, she answered curtly. The flood shivered with rage and Kairi leant forwards, extending a hand towards it. It swiped at her, missing her by less than an inch, but it was too close to avoid her when she reached out to place her hand on its forehead. Just like the shadow in the bathroom she felt a rush of raw, unbridled emotion surging from under her fingers. The flood wasn't just angry, it was fury unleashed. Rage at Xehanort, at his experiments, at the thought of being nothing more than a lab rat – a subject in a test. Rage that she had survived through sheer luck – through a chance encounter. Rage for the other children, their names and numbers unknown, who had been lost to the darkness.

Kairi closed her eyes and took a deep breath, pushing back against the connection. She hadn't crossed Aqua's path by chance, it had been an intervention of fate. And even if it had been luck, it had still happened, and Aqua's spell had saved her life. The experiments were awful, and the forgotten details were no doubt best left unremembered, but without them she never would have found Sora or Riku. And as for the children… there was little she could do but keep the thought of them close to her heart.

When she opened her eyes the flood had changed. The purples and blues and blacks had given way to pink and cream and white. It clambered up her arm and nestled around her neck where it seemed to sigh, content, before slowly fading away. Her chest swelled with a warmth that washed away the last of the aches left by the unversed's earlier destruction and Kairi smiled, resting a hand over her heart.

Stop doing that, Vanitas snapped.

What?

Changing them, he answered. She slowly rose to her feet and stretched some of the aches from her cooling limbs.

Can you feel them when they change? she asked.

They feel wrong, he answered curtly. Before she had a chance to question him further, he added: We should move. Something is stirring in the cottage. She glanced up the hill to where a light was glowing dimly through the cottage windows. It was a familiar, comforting sight.

I don't think we need to worry, she said. The cottage feels safe.

And the lab felt dangerous, he countered. Just because you've got some distant memory of a friend living there doesn't mean they live there any more. Let's move. Her smile soured a little as she considered his point. He was right, of course. She turned quickly on her heel and summoned her glider to rush back to Merlin's house. She slid back through the window and latched it silently. The room was undisturbed.

Vanitas?

Yes?

The way you trained me… Is that how Xehanort trained you? He was silent for a long while; long enough that Kairi wondered whether he was going to say anything at all.

You should get some sleep, he said at last. An hour or two is better than nothing. It wasn't hard to hear what went unsaid, and Kairi didn't press him further on it. It didn't matter. She changed back in to her pyjamas and slipped back under the covers.

Vanitas?

What? She chuckled at the irritability in his tone.

Thank you, she said. You really helped me. She felt his discomfort and she smiled to herself, burying herself deeper under the mountain of blankets. Sleep came much easier now, with a quiet heart and a calm mind; already she could feel it pulling her in to its warm embrace.

You're too reckless when you fight, Vanitas murmured. Kairi chuckled under her breath and wriggled deeper in to her cocoon of blankets and pillows until she was completely submerged.

What do you expect? I learned from Sora. He didn't respond, but Kairi didn't miss the flare of amusement that surged through his heart at the thought.

Vanitas going all out with the Tough Love approach. He's a little rough around the edges, but he means well.

I'll hold my hands up and say that I've never read the manga (if anyone can point me in the direction of where I can read it online, I'd be grateful) but a lot of inspiration for this chapter came from reading around the subject accompanied by various forum, Reddit and Tumblr posts.

Kairi returning to the lab and starting to find out more about her past wasn't due to start happening for a little while yet, but as I started writing this chapter it suddenly made more sense to place it here. It's out in the open now, and surely there's nothing worse that Kairi can discover about her past, right?

Smash that review button and let me know what you think! (Please! Pretty please! I gotta know!)