Riku summons all the power within her she can and calls both Keyblades to her again. Young Xehanort, fueling with rage from when she burned his face, holds his Keyblade up, the blue cord is ready to strike as well. Riku runs forward then and Young Xehanort rushes forward to meet her, he swings his Keyblade and the cord swings at her. She jumps over it and jumps back as it swings back around.
Young Xehanort pulls the cord back and and slices his Keyblade across her shoulder, or he tries, because she blocks him and locks his blade with one of hers and she then tries to attack him with her second Keyblade, and it hits and he pushes down on her, knocking her down and he goes to stab his Keyblade down on her and she shoots him with light and he stumbles back.
Riku quickly stands and shoots more light at Young Xehanort and runs at him, and while the light is momentarily burning or blinding him she attacks, hitting him with both Keyblades, she knocks him into the sky with some aerial move she used and she jumps up after him and tries to attack again, and she gets another aerial combo hit before he hits her, knocking her back to the ground and she lands on her feet and jumps back as he lands where she was.
She uses Cure on herself and runs at him again. He shoots darkness at her and she dodges it and keeps running. He unleashes the cord again and swings his Keyblade, the cord going right at Riku. She tries to jump over it but it wraps around her foot and slams her into the ground. She gasps in pain and then he sends a wave of electricity through it and Riku screams. Celius sends a burst of light at Young Xehanort, and it hits him, causing him to drop his Keyblade, having not expected an attack from Celius, who is almost twenty feet away from them.
Riku gets the cord off her leg and it retracts instantly. Young Xehanort sends a burst of darkness at Celius but Riku deflects it, "He isn't in this."
"He attacked me, so yes he is." Young Xehanort replies.
"You try to attack him you'll be deader than you will be when I kill you." Riku says.
Young Xehanort smirks, "That didn't make sense."
"Die!" Riku growls, shooting light attacks one after another.
Young Xehanort blocks her attacks, having to stay on defense so he won't get burned and Riku runs at him, still shooting light the entire time. She gets up to him and Attacks, slicing across him, from shoulder to opposite hip. He hisses and jumps away from her. She runs at him, not going to give him an opportunity to get away from her this time. She knocks his Keyblade out of his hand with one of her Keyblades, and she thrusts her Keyblade into his chest.
Riku jumps back from him and runs over to Celius, "Kill Vanitas and Isa, don't worry about Xehanort, just kill those two!"
"How? fighting them will take too long!" Celius frowns.
"Yeah, I'll do it." she sighs and brings her Keyblades up, pointing each one at Vanitas and at Isa.
She charges light balls at each end and closes her eyes, gaining all the light she can muster within herself. The blasts shoot off and hit both enemies in the chest and they erupt in darkness. Riku frowns and turns to Young Xehanort, who, although he is covered in dark flames, is still alive.
She groans, "Ugh, I'll finish him off. Wait here.."
"Okay.." Celius frowns.
She runs over to him and shoots light at him then rushes in closer and stabs both Keyblades into his chest. She jumps away as the dark flames grow and devour him. He disappears and Riku runs back to Celius. He gasps, seeing that Dawn/Xehanort has disappeared and so has his Keyblade. A light is shining from Riku. She frowns, unsure of what the light will do, but she sighs, already knowing what will happen now. She looks around her as The World That Never Was starts to fade, the building start to disappear, the ground starts to turn to gravel and then disappear itself.
She looks back at Celius, "I guess we disappear now too..?"
The light sprouting from Riku continues to get brighter and soon enough almost everything is illuminated by it.
"This is it then.." Celius takes Riku's hand, "Everything will reverse itself."
"That's the plan." she smiles sadly, "Everything will be okay again."
The light shines brightly and Riku and Celius are lifted into the air as the ground is all but gone.
Celius frowns, "If you're out there somewhere, when this is over, I'll find you, I'll come back to you. I promise!"
"I know you will." she smiles, "I know you will."
Then everything is consumed by Light and Celius and Riku are pulled in different directions as time rewinds itself.
A/N: Sorry it's shorter than normal, but this is it, one last chapter, I'll update that later tonight, so look out for it. Have a nice day and don't forget to review! ^^