A/N: Just a little Skyward Sword vignette, since I didn't find the official manga very fulfilling.
An age upon an age ago, before Nayru started time, the Golden Goddesses entrusted the land to their two younger siblings, a twin brother and sister. Both wanted to rule a world of their own, but their older siblings insisted that they must learn how to care for one first. And so each of the Three left one small piece of their power, to breathe life into the land and keep it alive. Since these pieces each contained the Goddesses' force of will, anyone who laid hands upon it could shape the world however they desired. But the Goddesses told their siblings that there could be no easy way of running a world, and so the Triforce was to be merely guarded by them, never used.
The girl twin's name was Hylia, but her brother's original name was lost to antiquity. From the very start the two of them quarreled; who would make the sun rise, who would change the seasons, who would scatter the seeds of life and who would extinguish their flames. Each one grasped half the world, and each one began constructing a very different place. Where the two met, nothing lived or grew, the bare stone splintered, and even the wind seemed to creak and groan as one side pressed against the other.
Exasperated, the Three split apart the land where the two joined, so that there were now three planes of existence. "You shall govern the Sky," said Nayru to Hylia. "You will control the Sun and the Wind. From you will come the beginnings of Life, in the Rain that falls upon the Earth, and it is in your realm that the mortal spirits will dwell before they mark their time upon the ever-changing plane."
"You shall govern the Earth," said Din to Hylia's brother. "You will control the Moon and the Darkness. From you shall come Fire and Death, but also the metals and the minerals upon which all living things must feed."
Standing on the middle plain, Farore said, "Here is the Land, which will only bear fruit when your two sides are in perfect balance. Too much Fire will burn it; too much Rain will wash it away. This Land will gauge how well you are caring for your world, this delicate thing that We leave in your care."
At first the two siblings were happy with this. They both tended to their own plane, and each of the two began to resemble the other less and less. Hylia's hair turned golden like the sun, and her skin became light. She garbed herself in white and masked her power with a thin, wispy frame. Her brother's skin grew scaly and black, his hair turning the color of flame. His body reflected the force within, and he wore dark clothing to match his skin.
But soon their rivalry got the better of them. Even though there were several sentient races living upon Farore's Plane, each of the two wanted to create another in their own image. Hylia created the Humans, weak in body but strong in mind, capable in combat but more given to song and art. Her brother created the Demons, loyal and strong, keen fighters able to build machines and move mountains.
The two brought their creations to the Land and let them run free. Hylia's brother laughed as the Demons drove the Humans across the plane. "See, Sister! Mine are superior to yours. They can tolerate the hottest sun, go for weeks without rain, and fight until they tear themselves to pieces!"
Hylia scowled, but did not consider herself beaten just yet. She bestowed upon her chosen ones Knowledge, of weaponry and defense, and instilled upon them ties of Kinship and Friendship. The Humans banded together and began to force back the Demons. "Where are your boastful words now, Brother?"
Her brother was not impressed. "Hmph! They are incomplete. They cannot fend for themselves; they must always have you watching over them."
"It isn't true! A little more time, and I can make them able to fight anything you could ever create!"
"Very well then!" He laughed. "Do what you can, and then bring them to the Land once more!"
So Hylia flew back to the Sky, and spent many long hours trying to perfect her Humans. Her brother worked hard too, but he had tired of this game. His creation had been superior from the start; as far as he was concerned, that meant he had the right to take the new world for himself. And so as he worked, he plotted not only to win his rivalry with Hylia, but to take the Goddesses' Will and use it to create a world that was only his.
So when they met on Farore's Plane again, Hylia's brother pushed his Demons forward and tore it apart. He took the pieces and began to build a bridge, up to the hidden plane where the Three had left their power. Hylia fought him with her own creations, but realized very soon that she was going to lose. She brought her Humans up to the Sky to keep them safe, then returned to the Land and fought her brother herself.
The two of them tore apart what was left of the Land, fouling it with their blood and destroying all that the Goddesses had created. The Three returned in wrath and separated the two siblings, shrieking in anger and weeping over the destruction of their creation. They talked and talked with the twins, but it became clear very early on that the two sides were irreconcilable.
Finally, Farore took one of her hair-pins and thrust it into the ground, creating a holy blade small enough for a mortal to wield. Nayru and Din each took a Human and a Demon from their creators and combined them to create a Warrior, a creature with the strength and stamina of Demon, but that was Human in all other ways.
Said Farore, "Hylia, your brother's power is greater, but we told you both from the very beginning that we wanted you to rule this world with equal force. So I am giving you this Warrior, who will fight on your side, but who will only exist on your brother's terms. He will only appear when your brother's strength overpowers yours."
Her brother was not happy with this, and demanded of the Goddesses, "If I have the superior power and the superior creation, why can I not take this world for my own?"
Nayru scolded him. "Superior in strength you may be, but you still do not have the knowledge and compassion required to be the sole God of a world. And so this will be under Hylia's rule, but it will not exist without you."
Furious, the brother replied, "If this land must be under Hylia's rule, then I will be its Demise. I will bring forth Disease, and Decay, and War and Famine and Death!"
"Bring forth what you will," Nayru replied, unimpressed. "It is your duty to do so, and keep this world in balance. With you on one side, and Hylia with her Warrior on the other, it should be just enough."
Demise lunged for his sister, but she shielded herself, and her Warrior struck him full between the eyes. The force of the blow scattered the Warrior's body, but his seal held and Demise remained stuck within the Earth. Hylia returned to the Sky, her power spent. She knew that the seal could not hold her brother forever, so she began knitting together the spirit of the Warrior inside the bodies of her humans. Over time, the pieces would come together to form One, and he would be born again.
But she knew that he would need to be still stronger when he arrived to fight Demise again, so she used the last of her power to put together an elaborate series of tests. At the end, her Warrior would have the Courage, Power, and Wisdom to match anything that her brother might bring to the battle.
The Three watched her fade as her spirit waned, and took pity on her. "Though this world cannot exist without your brother, we will entrust guardianship of the Triforce to you. You must never use it yourself, but you must keep it away from him, for you cannot trust him to leave it be as long as he exists. "
"Forgive me, Elder Sisters," said Hylia as her power began to leave her, taking refuge instead in the people and the Warrior's Trials that she had created, as well as servants to guide both herself and the Warrior when they awakened. "Alas, I am afraid your world will never be the beautiful place you hoped it to be."
"Do not despair," said Din. "The two of you are doing exactly as you should. We only regret that we had to intervene, for both of you are still too young to create your own worlds."
Hylia felt some comfort then, as her spirit became dormant and waited for the time when it would awaken once more.