"Wake up Sora." Sora's body lay prone in the middle of a barren wasteland. A figure, a little larger than him, was dressed in armor that completely masked his features and body. "Sora, you have to wake up." Groaning, Sora slowly began to awake. The armored figure nodded "Good. Sora, you've failed. Your heart was almost destroyed. I'm here to give you a second chance. But only if you can win." Sora had a lot of questions to ask but he didn't get to bring up any of them before Ventus summoned his keyblade. He swung it quickly but Sora managed to block. "Who are you!" Ventus pushed Sora back "It doesn't matter if you can't win!"
Sora brought out his other hand to summon Oblivion and replaced his Kingdom Key with Oathkeeper. His clothes turned red and he launched himself over Ventus's charge, landing behind him. Ventus spoke calmly "Valor Form… that one failed." With amazing agility, the figure turned around and leapt at Sora, turning his body horizontal to kick Sora directly in the face. Stunned, Sora fell back. Ventus used his weapon to knock away Sora's defending keyblade and knocked him down. "Sora, that one wasn't enough. Nor was Wisdom Form." He didn't even turn to look at Sora, now in blue, who had moved behind Ventus in a flash of movement. Sora glared "Fine then, how about this? Master!" He leapt in the air, only to find the armored figure apparently standing on nothing. "Don't you remember, Sora? This one didn't even defeat Vanitas. There's no way it could stand up to Xehanort." A powerful strike sent Sora into the ground.
Darkness began to gather around Sora. Ventus looked around "Your heart has been corrupted by darkness before and still lingers. You have to get the better of it." He turned to watch Sora turn into his Anti-Form. "Darkness cannot be used to defeat darkness." Sora disappeared, only to rake Ventus's arm a second later. Then his speed slowed as wind gathered around him. "I may not be able to stop you but the air around you can certainly slow you down." Ventus's weapon managed to wound Sora before he got away. Again and again, Sora attempted to strike and each time, Ventus managed to use the wind to slow him down enough to counter attack. Then a whirlwind surrounded Sora. "Sora, this is the end." Ventus pointed upward. While they had been fighting, a mass of wind had gathered and been compressed. Held by the wind, Sora could do nothing as the mass pushed him into the crater it was forming.
Ventus walked to the edge of the crater, looking down at Sora as the darkness dissipated. He spoke softly "C'mon Sora, you can do better than this… please." Then light erupted from the crater as Oblivion flew at Ventus from his side. Sora rose from the crater, his clothes silver. His two keyblades circled around him for a moment, then homed in on Ventus. Under his armor, Ventus smiled. "There you go Sora…" He disappeared as the keyblade pierced him. In the outside world, Sora again took control.
Xehanort frowned as the heart protecting Sora's disappeared, leaving a healed heart behind. Blinding light shone out of the cage of keyblades, then an explosion sent them flying away. Dust raced through the air as Sora was revealed, his silver clothes fluttering. Xehanort shook his head "Whatever you do, you are no match, boy!" His fingers danced and the keyblade gathered again.
Sora looked at the weapons with a frown "Those don't belong to you." Xehanort's eyes opened wide as several of the keyblade tore themselves from his control to circle Sora. A keyblade of bone, a keyblade with a pumpkin, and a heart-covered keyblade were three of the ones surrounding him. These keyblades shot towards Xehanort's keyblade attack and managed to repel all of them. Then Sora held out his hand. A keyblade tore itself from the ground and entered Sora's grasp. A light swing carved up the earth as the keyblade was revealed. It was a brilliant blue and gold color, woven in a complex pattern. The UItima Weapon. Xehanort suddenly felt doubt enter his mind. "Enough of this!" He launched a ball of dark magic which Sora casually deflected. He stuck the keyblade into the ground. Lines extended from it to two other locations. Looking around, Xehanort found that Oblivion and Oathkeeper were similarly planted. Never looking away, Sora spoke two words as power gathered "Trinity Limit." The energy consumed Xehanort, blasting away the darkness.
((Both criticisms and advice are very welcome either by PM or review.))