As Sephiroth stood over the defeated party, preparing to strike the final blow with his mighty Masamune, a single sunbeam parted the thick grey clouds. A single figure descended from the heavens on sparkling white wings, a chorus of angelic song heralding her approach. Her cascading midnight-black tresses shimmered in the sun. Her innocent, glowing amber eyes sparkled with wise, innocent sorrow.
"I am Purity Moonbeam Kotowari Rainbow Cetra Aurelia Zu! You have been a pawn of darkness for too long, Sephiroth, and it is my duty to purify you!" the girl cried in a voice like silver bells, pointing dramatically at the silver-haired ex-SOLDIER. Her silvery robes billowed around her, the diamond sitting over her heart flashing dramatically.
What on the Planet is she? wondered Vincent Valentine from his position on the sidelines. To interfere in this kind of fight... she must either be mad, or very powerful...
Sephiroth looked bemused for a moment, but his face quickly regained its megalomaniacal smirk. "Foolish girl. Do you truly believe you can defeat me? I am a god!"
Purity shook her head, smiling slightly. "I don't want to defeat you, Sephiroth. I just want to cleanse the evil of your heart so you won't hurt any more people." With those words, the angelic girl raised her hands, which began to glow with a soft pearlescent light. Cloud, Tifa, and Yuffie stood up, watching as the glow grew stronger and stronger. After a few minutes, the light finally hit its climax.
"Niji shōkan yūjō bīmu!" exclaimed Purity. A glowing ray of coruscant multichromatic light emanated from her hands. The beam struck Sephiroth - who had been rooted to the spot, trying unsuccessfully to move ever since the lovely young woman had began casting her spell - engulfing him entirely in a rainbow glow. The aqua-eyed Adonis cried out in pain as a stream of some dark, inky, vile liquid was ripped out of his chest and floated across the beam to the jewel adorning Purity's chest. The black also flowed away from Sephiroth's clothes, so now they were white. The beam dissipated as the blackness began to swirl around the inside of the diamond until it was absorbed by Purity's pure heart.
"Wh- what did you do?" asked Sephiroth. Masamune fell from his nerveless hand, clattering to the ground. Purity's redemption magic had drawn out the darkness from him, making his heart and his clothes as pure as the driven snow. "Oh Planet, what have I done? All those people... everything I did... I'm so sorry!"
Tifa glared at Sephiroth. "Sorry doesn't even begin to make up for what you've done to Nibelheim or the Planet!"
Cloud nodded in agreement. "The man who I saw burn Nibelheim would never really regret what he did. He has to be lying."
"But-" Sephiroth began, but he was cut off by Tifa.
"You tried to murder everyone on the planet! You managed to murder everyone in Nibelheim, and Aerith! And you expect us to forget that because you say you're sorry?" the martial artist began to laugh hysterically.
"But sh-" Sephiroth attempted again.
"Tifa is right, Sephiroth. The only redemption for you is death," Cloud said solemnly, hefting his Buster Sword.
"What I'm trying to say is-"
"Guys!" Yuffie interrupted, "behind you!"
Cloud and Tifa both spun around to see Purity standing behind them, hand outstretched and glowing with dark magic. The gem decorating her chest had darkened to a pitch black colour. One of the wings on her back had become spectral and immaterial, and the other was black as midnight. Her eyes were the same slitted blue-green as Sephiroth's, and her hair had lightened to the ominous colour of ash. Her once-girlish form had been twisted into a creature of death and decay.
The fallen angel hissed as she struck out at Cloud with her now-taloned hand. He began to raise the Buster Sword, but he wasn't quick enough. Time seemed to slow down as the spiky-haired hero saw the glowing talons move towards his throat.
There was an awful screeching sound like nails on a chalkboard as Purity's talons were deflected by the Masamune an instant before they would have pierced Cloud's neck. As Purity leapt back, Sephiroth followed her, his blade glowing blue as it swung towards her.
One short, brutal and awesome fight scene later, Purity lay lifeless on the ground, her silvery robes tattered and torn. The shining blade of the Masamune ran through her chest, through the fractured jewel over her heart and into the earth, pinning her in place. Blood flowed from the wound in her chest and countless smaller cuts all over her body. The group of heroes (and Sephiroth) stood bloodied but victorious.
Then canon resumed without incident, but Sephiroth's trenchcoat never did turn black again.
Author's Note: My first fic! Did you like it? Please review! I have no idea what I just wrote, lol, and it's past midnight right now but I want to post it before I lose my nerve! But please don't flame because I'm really insecure and it hurts my feelings and only mean people flame and I'll get really sad if you flame. Nice reviewers get a virtual cookie! Flamers will be impaled on random objects, as is the fate of all who oppose the mighty Sephiroth (except Cloud).
Actual Author's Note: Please ignore everything written above except the part which says "I have no idea what I just wrote". Thank you.