A/N: Been a while since I've written anything for this fandom, but I'm back with a little something. :) Tifa is my favorite character from this series (as many of you know), and I always love writing stories centred around her. So, this is my take on Advent Children, with a twist.

"Underneath the skin there's a human
Buried deep within there's a human
And despite everything I'm still human
But I think I'm dying here..."

-animal, daughter

Advent Children: Secrets of a Locked Heart

Prologue: Black Butterfly

She wanted to sleep.

It was her time, she'd lingered long enough, and she was so very tired. The ebb and flow tugged at her conscience, sang her a lullaby that freed her of all her aching memories. They became a part of one another, melded together. She could feel herself slipping, and it was calming to float there in the waves as they crashed softly against her.

She was ready to go.

Bu there was a disturbance, then.

She could feel it, slight though it was, like she always did. It was enough to jolt her, to fight off the sleep that plagued her. Her duty was to keep it in check, keep its insatiable hunger always at bay. She seeked for it, probed for it with her mind, fearing the worst. It got stronger as she moved along, pulsing to life with every oncoming wave; an indicator that she'd failed this time.

Anger.

Hate.

Vengeance.

So much of it, overwhelming her all at once until she was left drowning in it. No longer was the flow calm; it raged as if a storm was on the horizon, and she tried to fight it, to claw her way to the surface. She struggled against its evil current, and all of it came back to her in a single movement. No longer was there peace.

She was drowning in the thick, black liquid. Like a poison, it seeped and contaminated all around it. The first memory that came back to her, was always the same one. She knew then, she wasn't ready to leave just yet. Her work wasn't done. She couldn't leave him.

Cloud.

Her memories echoed the name, rebuilt the image of glowing cerulean eyes, wheat coloured hair, upturned nose, ribbon shaped lips. She sent it into the ripples across the waves, and it was perhaps, her first mistake.

As soon as she recalled it, the waves around her grew more violent and angry. They twisted and contorted, confining her within them, like a whirlpool she could not escape. They joined her conscience in speaking the name, building the memory. Except, the voice was full of loathing and evil. It drowned her out, took control, and she was left powerless.

Help!

She needed help. She had to find a way out, had to stop the contamination. It told her it was too late. The poison had reached a substantial amount, and there wasn't an ounce of purity left. But she had to protect him, so she fought against it anyways; a battle she could never win.

The storm raged on, spinning her about, toying with her. She had just been ready to sleep...

It quieted her, wanted her to stay out of the way. No more meddling from the Ancient powers. She moved against it until she could move no longer. She floated, helplessly, lifeless. But she could still watch as it worked.

She saw the thin, black like fingers spawn through the luminescent green, stretching as far as they could go. All the while, they echoed the name, remembered their hatred for the one responsible. With her out of the way, it was only a matter of time...

It would find its path to him, no matter who it got to first. It would find him sooner or later. It had a plan, and casualties weren't something it cared for. It would eliminate all who stood before it.

There would be three pieces.

It flowed in three different directions, infecting all it could.

Three instruments, one vessel. It was not afraid to let her glean that much of its plot when it's conscience fused with her own.

To accomplish the impossible, that was what it required.

She was the observer now. By the time she would be able to break free, it would be too late...

It had already found its first mark. She agonized at the thought of the children. Malicious and cruel, it cared not for whom it bestowed its kiss of death.

Her last thought was the same as her first one...

I'm sorry, Cloud...

It looked like a butterfly.

Small, black, in the centre of her back and along her spine, its wings stretching outward. It marred her once fair skin. Barely noticeable. But it was there, and that was how it had started.

It didn't hurt yet. Didn't even beckon an itch. Maybe it would go away, fade away into a scar, like the many that already decorated her skin.

She examined it in the bathroom mirror, indifferent. She rubbed it, touched it, watched how it was so perfectly imbedded into her body. It moved this way and that, stretched with her. Anyone could have assumed it was just a birthmark, or a beauty mark. But she knew better. The suspicious little symbol had only recently become a part of her.

She'd stayed optimistic. It hadn't grown much in size over the past few weeks. There was no need to alarm anyone. She'd kept it to herself this long, she may as well hold on a while longer. It was possible that it wasn't a symbol of the rampant, infectious and deadly disease. Or so she liked to tell herself. She'd experienced none of the similar symptoms, although she was aware that each and every case was unique to the individual. In a strange way, it was still beautiful. The thought was strange and foreign to her, but it was there.

She caught herself staring at it, entranced by the uneven lines and curves, and the way it blended with her. Where it ended, and she started. For a fleeting second, she thought she saw it move, pulse against her like a parasite leeching her very life. She rubbed her eyes, and figured it was because she hadn't blinked. She was just seeing things.

It was best she told no one.

She convinced herself of it, even as she reluctantly put on her clothes. She would wear her smile, her cheerfulness despite the fact. She'd put on the show for her friends. It was bad enough that Barret worried about her incessantly. He was on Cloud's case for his frequent absence already. Were he to find out that she'd been infected, he'd blame his old comrade in a heartbeat. She didn't want them to fight. Things were hard enough as it was. And if Cloud were to find out, well...she didn't really know what to make of that.

Taking in a deep, shaky breath, she stepped out of the bathroom, and returned to her duties. The world wouldn't stop turning just because she was sick.

Still...

She couldn't quite shut the nagging voice in the back of her mind, telling her of her imminent doom, of the harsh reality, even as she worked the bar and poured the drinks...

Tifa Lockhart was dying.

A/N: To be honest, I'm not the biggest fan of AC. However, I did think it had a semi decent plot. There were certain aspects that didn't work well, in my opinion, so I'm obviously not going to be following through with it entirely. I'm making changes, adding twists, and basically creating something a bit more of my own. So no, this isn't really a novelization of the movie. We'll just see how it all goes. :) Feedback, as usual, is welcomed.