I couldn't remember if you fight Xigbar in the Hall of Melodies or Memories… Tell me! I'm going with Melodies, unless I'm wrong. Then I'll go with Memories.

The Hall of Melodies

Xemnas stood on the balcony outside the Proof of Existence, the Organization's "memorial hall" to its members. Below, Sora, Donald, Goofy, and Ansem the Wise walked into the Hall, unaware of his presence. On the other side, Riku and the King walked through the doors. "Riku!" Sora ran over to his friend, who drew the Way to Dawn. Sora watched as the Keyblade was devoured by darkness, reshaping into an older Keyblade. Riku held Ansem's Dark Keyblade, standing in a battle stance. The King jumped over him, landing in front of Sora. Mickey turned around, putting his own Keyblade between them.

"Stop!" His high pitched voice ordered. "Release Riku, now!"

"Release him?" A deep voice came from his mouth. Sora instantly recognized it.

"Ansem." Ansem the Wise pushed through them, standing next to the King.

"Xehanort. Release the boy." Mickey looked up briefly, then back at Riku.

"Ansem."

"I'm here, old friend." The halberd shone in the light of Kingdom Hearts above. "Let him go, Xehanort." Xemnas watched the scene below, mildly amused.

'Ansem. What a surprise.' He looked over to Riku. "And the Seeker of Darkness." He said to himself.

"I'm no longer Xehanort." Riku answered. "I'm Ansem, the Seeker of Darkness."

"What do you want?" Mickey shifted to a more closed position.

"Kingdom Hearts, nothing more." Riku looked up to the moon.

"Good luck!" Sora attacked him, Riku blocking with his Keyblade. "You're not getting that door. I defeated you once, and I can do it again."

"Good luck." Riku smiled, palming Sora's chin. He stumbled back, Riku coming in fast. The King jumped in, blocking the attack. Ansem came up behind, Riku spinning around to block the attack. He jumped up into the air, dark energy shooting out as he landed. Sora jumped back, Ansem flipping back off his lance. The King soared over Riku, landing on the other side. Riku turned on landing, hurling the Dark Keyblade, Dark Raid knocking the King off his feet.

"Your Majesty." Sora ran to Riku, Driving to Valor form. Riku intercepted him, pushing with the same force of both Sora's Keyblades. The Oathkeeper and Oblivion strained under the Dark Keyblade, giving out as Riku knocked him back with Dark Firaga. The Oblivion glowed blue, the Keyblade shortening. "I'm finishing you, now." Riku charged him, Sora attacking. "Ultima Blade!" Riku blocked it, the blue aura dispelling.

"Even Ultima magic can't save you now." He pushed down on the single Keyblade with his own. Sora swung the Oathkeeper, Riku catching it with his hand. Ansem flung him off with the halberd, Mickey getting a hit in midair.

"Magnet!" Donald pointed to Sora, Riku flying over, hanging in the air. Sora slashed out, Riku blocking every attack.

"You're not fast enough." Riku broke out of Magnet, flashing out of vision. He appeared briefly, shooting right in front of Mickey before disappearing.

"Dark Aura. Watch out." Ansem swung, parrying a strike. Sora rolled out of the way, narrowly being missed. Donald was hit, the King catching him.

"Thanks, your Majesty." Sora pushed Mickey to the side as Riku rushed past them. Everyone waited, nothing happening. They looked up, Riku falling from the ceiling for the finisher. He slammed into the ground, dark energy spiking out of the floor. Ansem grabbed him by the neck, throwing him into the air and knocked him over to Mickey with the halberd. The King jumped up, grabbed Riku, spun him in circles, then threw him over to Sora.

"Sora!"

"Drive!" Red changed to yellow as Sora changed to Master. He jumped up. "Ultima Sword!" Both Keyblades radiated blue, grabbing Riku and slamming him into the ground, Ultima pushing him into the floor. Sora and Mickey stepped up to him, pointing their Keyblades.

"This is the end, Ansem."

"The light of Kingdom Hearts vanquishes you, never to return." Riku smiled, then laughed.

"You can't relinquish me. The boy's heart will collapse." Sora and Mickey looked at each other, then back down at Riku. The Keyblades glowed, shooting beams of light into Riku's chest. Darkness flowed out, dissipating into the air. Riku reverted to normal, changing back to his jeans and jacket. He groaned, pulling himself up.

"What happened?"

"You drove into the darkness too much, being overtaken by it again." Mickey helped his friend up. "Ansem resumed control of your heart, trying to take Kingdom Hearts for himself." Riku picked up the Keyblade, the darkness melting away into the Way to Dawn.

"Very good." Xemnas clapped his hands from the balcony, everyone looking up.

"Xemnas." The King said.

"Xehanort." Ansem stepped forward. "Why are you doing this?" Xemnas laughed.

"Why? You haven't figured it out yet?" There was no answer. "Then let me explain it…"