I recommend you get on YouTube and look up "KH:BBS OST Rage Awakened" and listen while you read. I listened while I wrote and it helped me set the mood of the battle.
Chapter 20: Rage Awakened
Rytex started laughing.
"Maybe it's time I shared with you my real plan. See, I knew my other self's execution was coming in this world. If he died, I would vanish. I am a sentient being, but I am tied to him. I needed a vessel of great power to cling to when my other self was killed. The King was a prime choice, but he wasn't powerful enough. When I saw you return, I knew you came from Cryonia, which was where people of incredible power were supposed to live. I needed a way to get you back. Fortunately, the King served a purpose. His nephew was betrothed to your beloved and he was jealous of you. He also had the power to allow me to send you running. And so I sent you running. And you ran just where I thought you would run. However, I needed a test for this boy, Rytex. When the Hylian Navy attacked the small hamlet you call home, I possessed a soldier and fought Rytex. He was just the person I was looking for. Incredibly powerful, and with a certain darkness to him. When I returned to the King's body, I knew you would plan to come put an end to my presence in the King. So I made preparations for this. I became very learned in the art of Soul Transplant. I invaded his body, as you can see. Now, I will survive my other's execution and continue to work toward the Triforce!"
He began to laugh maniacally.
Rytex's Blood Sword appeared in his hand.
"And the first thing I'll do is this!"
He waved his empty hand through the air.
Link felt darkness weave itself around his arms and bind him in place.
Ganondorf held up the Blood Sword, ready to stab Link, but faltered.
"N- no! Your body... has been stolen and your soul was too weak! How can you... still fight me!" he shouted.
Then he raised his empty hand.
An ethereal key appeared in it. It looked like it could be used as a weapon, but Link didn't know what it was.
"No! Get out! Begone!"
Then Ganondorf stabbed himself with the key.
There was a blinding flash of light.
Out from Ganondorf's chest came a white orb.
It settled next to Link and transformed into Rytex.
He was sword-less and stared at Ganondorf with a mixture of rage and sadness.
"No! You'll do no harm to my friend!" he shouted, lunging at Ganondorf.
Ganondorf laughed and held out a hand.
"To the Ultimate Darkness with you!" he shouted.
A portal of darkness appeared and began to suck Rytex in.
Rytex fought, reaching for Link, who reached back.
But when their fingers were about to touch, Rytex flew back into the portal and closed.
"No!" shouted Link.
The binding darkness vanished.
Link charged Ganondorf with the Master Sword.
A furious duel ensued.
Rytex had been athletic and incredibly strong and fast. Ganondorf's presence had only amplified that.
Link and Ganondorf exchanged blows and blocks.
They were evenly matched. Neither could get an advantage over the other.
Link fought as hard as he could, and even harder, determined to defeat Ganondorf and expel him from Rytex.
Finally, Link slashed downward. Ganondorf made the move to block, and Link redirected the blow sideways, hitting Ganondorf in the thigh.
Ganondorf howled, then began uttering short words in a foreign tongue.
"No!" shouted Link, recognizing the words as an incantation for teleportation.
Link lunged forward to stab Ganondorf and end his hold over Rytex.
He was too late.
Ganondorf vanished, laughing into the sky, as the sun rose and morning came.
End the Climax. R&R