A/N: Guess who's foolishly starting another multichapter :D So this is the Vanitas-and-Aqua-merge story I've been wanting to tackle for a long time. (Sorry, Unplanner, "SAGS" didn't make the cut for the final title xD) I kept putting it off because I had higher priority stories (...which I still do), but finally I just decided I had to write it anyway. I'm not abandoning "Stroke of Midnight," and I'm still working on the CaS-prizefic too, but I had to get at least some of this out of my system first.

This will probably end up being a strange mix of dark and awkward, just considering the possibilities of Vanitas and Aqua sharing the same body. *sweatdrop* So yeah, just a warning ahead of time.

This starts off right in the middle of BbS's finale at the Keyblade Graveyard.

"Go take what Ventus owes you. And take Aqua's life."

Finally. Vanitas nodded sharply before running towards the edge of the cliff. Terra pursued, but Vanitas didn't worry about that - the loser was too slow, even if Master Xehanort hadn't been around to keep him occupied. He grinned beneath his mask as he dove from the cliff, feeling the wind rush around him.

Wind. Ventus. His old name. Soon to belong to him again.

His grin only widened when he realized who was in the path of his fall. Really, they were making this too easy for him. He flipped in midair, readying his blade to strike down on the girl's unprotected skull -

"Aqua!" Ventus shouted from the ground, and she looked up with a gasp. Just in time to see her destruction descending from above.

Or, just in time to stop it. He grit his teeth as her blade intercepted his, metal screeching at the contact. His feet crashed to the ground seconds later, sending a shock up through his knees.

"You!" Aqua spat at him. Her eyes were just as fiery as the last two times they'd fought. It would be a pleasure to get to extinguish that flame once and for all.

"Missed me?" He smirked, not that she would be able to see. She shoved her keyblade against his, and he jumped back. Though irritated that he would have to wait more long seconds to merge with his other half, part of him was glad that she had intercepted his blow. After their previous encounters, it would it would be a shame to pass up one last thrilling battle. Adrenaline flooded his blood as he took up his taunting stance.

"How are you still alive?" She shouted even as she was already shooting blasts of Firaga towards him, not taking any chances this time. He snorted and cartwheeled out of the way.

"You really thought you finished me in Neverland?" He teleported behind her, then brought his keyblade down in an overhead blow. She twisted at the last second and took it on her armored forearm, which dented at the impact. "That was just the warm-up round."

"Aqua!" Ventus called from behind her. Vanitas rolled his eyes; his pathetic other half was still frozen solid. Thanks, Xehanort. Freeze the idiot and drop him off a cliff; that's a great way to protect your precious X-Blade. If Aqua hadn't caught him, he would have had to go with his riskier backup plan.

"Shut up. You can't do anything for her," he said, springing back to avoid Aqua's barrage of strikes. She'd gotten faster since their last fight, he noticed. Braig hadn't done a very good job of wearing her out.

"Stay down, Ven!" She called back to him. "Let me handle this!"

Vanitas chuckled and aimed a ball of dark fire at her, but she dodged and retaliated with magic of her own. Her quick Thundaga jolted through him; he bit back a scream. Xehanort had done worse to him before. He could handle this.

He recovered quickly and sprinted forward just as she started glowing with her Thunderbolt command style. Would it have killed you to teach me how to do that, Xehanort? Her sparking blade arced towards him; when he blocked it, the electricity ran down his weapon and numbed his arm, but he kept his grip.

Alright, playtime's over.

"Suffer!" He cried, leaping and crashing down on her from above. He struck twice, but on his third attack she called up a barrier barrier that absorbed the hit, then exploded outward. The shards sliced through his suit, leaving new trails of red. He shouted and reknit the dark fibers as he lunged forward again.

"Heal!" A warm green glow surrounded her, and he cursed. Yet another skill Xehanort had failed to teach his apprentice. He tried to take advantage of her vulnerable moment, teleporting to strike from behind.

"Too sl-" He bit off the taunt when Aqua struck his keyblade arm with the shaft of her blade.

And then time stopped. Or at least, that was how it seemed. He couldn't move; he couldn't breathe. Panic rose in his chest, but he couldn't even release it as an Unversed. It was just trapped there inside him, the way he was trapped in his own body, unable to escape, forced to watch as Aqua rained blow after blow upon him, teleporting and leaving afterimages in her wake.

She - when did she learn how to do that!? He barely thought before time resumed, and the pain of each attack hit him all at once. His mind hadn't been prepared; he doubled over, nearly dropping Void Gear.

"Too slow," Aqua mocked back as a new aura of energy surrounded her - one he didn't recognize. Not that he could think clearly through the pain his body was still trying to process. Was he seeing double? Had she hit his head that hard even through his helmet?

No - there were two of her. More than two. With each move she made, a ghostly afterimage remained, like reality couldn't catch up to her. It looked almost like Vanitas's own attack, where he would leave an illusion decoy and strike from behind.

She… did she learn that from me? He wondered as he cartwheeled away, dodging her rapid attacks. There were so many illusions, it was hard to tell if he was avoiding the real one or not.

"Wow, Aqua!" Ventus cheered from the sidelines, still half-frozen. "You've got him now!"

Unfortunately, Aqua was beating him, for now at least. And he would still have to fight his other half after this. If only he had the X-Blade already! But he couldn't forge with Ventus yet, not when the idiot was little more than a popsicle, incapable of fighting back.

He tried to take the offensive, which was nearly impossible with so many phantom Aquas crowding the battlefield. He sliced through a few only for them to flicker like static and disappear. Then he finally targeted the real one, mostly because she brought the fight to him. Their blades clashed with sharp, piercing clangs.

They danced back and forth, blurs of blue and black, trading blows, parrying strikes, shooting magic. For a while and in spite of her illusions, Vanitas actually managed to gain the upper hand. There was a pattern to the phantoms, and once he saw it, it was easy enough to find the real one. And for whatever reason, she didn't come cleanly out of her cartwheels in this command style. Maybe she was still learning how to use it.

Just as she was looking ragged enough for him to end the fight, she unleashed her finish command. She leapt into the air and dove down over and over again, creating a star of magic that exploded with light at the end. Vanitas executed a sloppy cartwheel, just effective enough to dodge the worst of it. The light still burned his skin through his suit.

She came out of her finish breathing hard - but then again, so was he.

"Give it up already," she shouted, though her voice was hoarse from the dry air. "I'll never let you hurt Ven!"

Exhausted as she must be, her eyes still burned as fiercely as at the start of their battle. Maybe even more. And suddenly, he knew she was right. As desperate as he was to be whole, to unite with his other half, he would never be able to do it with Aqua still standing. Because somehow, against all reason, she was just as desperate has he was.

"Why do you care so much about that loser?" He asked, with equal parts spite and curiosity. "All he's done is use you. Hurt you. If it weren't for him, none of you would be in this mess."

"Aqua…" Ventus murmured from behind her, his face falling. "I'm sorry-"

"No." Aqua's eyes narrowed at Vanitas, though her words were aimed towards her friend. "I wish you would have listened to me, but this freak would have come for you regardless."

Vanitas ground his teeth against the insult. Somehow, of all the things she'd said and done, that barb dug the deepest. Probably because it was true.

But not for long. As soon as I merge with Ventus-

Which he couldn't do. Not until he defeated Aqua. And just like in Neverland, they were at a stalemate - only this time, he couldn't risk exerting all his energy on this fight.

Unless… I decide to take a different risk. Unversed of fear squirmed inside him as he thought of his backup plan. That plan could very well get him killed - but then again, if her and Ventus were too unbalanced, he could die from that union too.

The risk would be worth it. He had to forge the X-Blade - he had to. There was no other choice.

He threw himself back at her, ignoring the fatigue that threatened to drag him down. He had to give this fight everything he had - and he had to make sure she did, too.

"You really think you can save him?" He taunted as their blades locked again. His mask was only inches from her face. "There's only one way to stop me from killing him."

Her face hardened, her lips drawing to a thin line. "Whatever it takes, I'm willing to do it."

She cast Seeker Mine, sending pools of magic to home in on his feet and blow him back. He backflipped out of the explosion and landed on his feet, skidding back and throwing up dust.

"I hope you mean that," he said through a smirk. Then he slid forward in a powerful but reckless combo, his blade streaking so fast it nearly left afterimages without the aid of magic. She parried and dodged, and her armor absorbed the few hits she couldn't block.

I could use some armor like that. Well, if this worked, he might have it shortly.

Sweat dripped down her face, but she didn't give up. Good. Vanitas wasn't expecting her to. But she was still on the defensive; he needed to taunt her into retaliating again.

"Come on, Aqua. I thought you were the Keyblade Master here." His words produced a spark of anger in her eyes, but she quickly reverted to calm. That was the problem - in spite of the danger, she was still disciplined, still in control. Not as easy to unravel as her friends. But there was one thread he knew he could tug on.

He teleported behind her, but this time, he didn't go in for the attack. Instead he stood behind Ventus, raising his keyblade high over his chest.

"Aqua!" The other boy shouted, panic flashing over his half-frozen face. It was uncanny, seeing his old face stare up at him like that, practically begging for mercy.

"Pathetic," he spat as he quashed the conflicted Unversed inside him. "You always need your stupid friends to come save you. When are you gonna grow up?"

He didn't hear Ventus's reply - because at that moment, a giant crystal of ice burst from the ground, launching him into the air. He crashed to the ground a few paces away, gasping for breath. Then Aqua's metal boot was planted in his chest.

"You - will not - hurt him!" She snarled down into his face. His muscles tensed unconsciously, but he forced himself to keep his voice even.

"Then you're going to have to kill me, Master Aqua."

Her face stayed as hard as steel. "That can be arranged."

Vanitas's eyes widened. That was exactly what he'd wanted - for her not to hold back. But that look on her face… if she could look at him with that much hate, did she really have enough light to forge the X-Blade with him?

His mind hesitated, but her keyblade didn't. The tip of the cobalt weapon released a blast of brilliant white light.

Vanitas screamed. Every nerve erupted in pain. His heart released all the Unversed he'd been holding back throughout the fight, but as soon as they were born, they dissolved in the face of the scorching light.

And then, he began to dissolve with them.

Maybe… she does have enough light…

His last thought was to hope so. Otherwise, he'd just made the most foolish mistake of his life.