From the Imperial Archive, on the origins of Quetzalcoatl Victorious:

Huitzilipotchli, god of war, god of the sun, he who drove back the forces of night to save mankind had grown weak from his never-ending battle. The in-fatigable god had at last become tired and delirious. For days his fight his sister, Coyolxauhqui was erratic, the sun rising unexpectedly, the heavens swirling. The stars themselves re-arranged to avoid the blows of the mighty god. The people of the One World watched this fearfully, for if Huitzilipotchli were to fail, so would the fate of Human kind be sealed. Seeing this, the great Uley Tlotlani of Tenochtitlan sent his priests to pray to the gods to help Huitzilipotchli. They prayed for days, but the gods did not budge. Even the great Coatlicue would not approach her son, fearing he would mistake her for an enemy and strike out at her. This went on for some time, before Paynal, the messenger of Huitzlipotchli, came to Quetzalcoatl, the Feathered Serpent, ancient among the gods. “Oh mighty lord” Spoke Paynal, prostrating himself before the throne of the god. “My master has lost his wits! Oh Lord of Healing, Lord of Light, Lord of the morning star, I beg of you to help him! He feels no pain in his battles with his sister, the moon, Coyolxauhqui. He is delirious and will surely destroy himself and the One World if he is not healed!” Wise and gentle Quetzalcoatl heard this plea and spoke softly, as he often did, to Paynal. “Young Paynal, do not despair. For I will not allow the One World to perish. The men of the one world are of my bones and my blood. They will live and so will your master. I believe I know who has caused this mischief. I shall do what must be done.” With this said, the great Feathered Serpent spread his wings and left his throne to seek out his brother, Tezcatlipoca. Tezcatlipoca, The Lord of the Here and Now was the mighty creator god. His cruel hand was felt to be at fault when a rich man was brought to mis-fortune, when a might nation would fall or a great building collapse. When Tezcatlipoca chose to appear on the earth he brought destruction, and only rarely did he provide good fortune to an individual, after all why should he? When gentle Quetzalcoatl had heard the story of Paynal, he immediately knew this calamity must be the fault of his brother. Quetzalcoatl found his brother sitting on one of the many benches built for him by the men of the one world. He sat playing with the wreaths of flowers regularly set aside for him. “Mischievous brother”, spoke the Feathered Serpent softly and sweetly as he joined his brother on the bench “Why have you cursed our kindred. Why have you driven Huitzilipotchli to madness? He is the savior of the men of the one world and without him, they shall perish”. Tezcatlipoca snorted at this “Why do I care brother? What are men to me but playthings? What is Huitzilipotchli to me but a ravenous and angry youth? He fights his siblings like a vulture fighting for carrion. Let them destroy each other and end the fighting. It is bothersome.” Quetzalcoatl merely shook his head. “But brother, if the moon overtakes the sun or the sun overtakes the moon then the days of men shall end and all that will be left in the one world is the howling of the wind.” Tezcatlipoca did not respond to that, but began to laugh, and as he did the winds began to blow. "What does this matter to me? I do not require the blood sacrifice. Men are your playthings brother". Quetzalcoatl, finally understanding the plans of his brother, became angry. Men were of the bone and blood of Quetzalcoatl. They were his charge and his children, and the Lord of Mischief intended to end them forever. For the first time since the dawn of eternity the great Feathered Serpent spread his mighty wings, bared his black, obsidian fangs and battled with Tezcatlipoca. As the two brothers fought, the one world began to shake. The winds increased and the seas began to churn....and for a moment it seemed the one world would crumble. But such was the power of the mighty Quetzalcoatl and so great was the shock of Tezcatlipoca at his serene brothers anger, that the Lord of Here and Now was quickly defeated. Quetzalcoatl in his anger crushed his brother's body with the talons of the Feathered Serpent and thus Tezcatlipoca was vanquished and the Lord of Light became the chief god of all the Aztecia. But Quetzalcoatl did not rejoice. For he was a gentle spirit and the death of his brother left the world unbalanced. And so Quetzalcoatl took in the life force of Tezcatlipoca and with it the great responsibility for not only man, but the whole of the one world. But What of Huitzilipotchli? The Sun God continued to fight terrifically and the sun and moon were often seen in the same sky at the same time. Quetzalcoatl again spread his great wings and flew to the heavens. As he arrived the sibilings paused for a moment but there was no surcease to the fighting. "stop!" roared the great Feathered Serpent, but now Huitzilipotchli, not recognizing his better, attacked Quetzalcoatl. So the great Feathered Serpent threw the God of the Sun down onto the tiny island of Atzi outside of the city of Tenochtitlan. The Sun God was stunned but attempted to fight. The mighty Feathered Serpent grasped him gently in a single talon and spoke:
"Huitzilipotchli, through the machinations of my brother you have descended into madness. No more! For you and your sister will share the sky and no longer will the race of men be forced to sacrifice themselves to feed you. You shall share the sky in total accord, or all will suffer!" As the great Quetzalcoatl spoke, he removed a single obsidian fang and made a cut into his talon. From this he fed Huitzlipotchli and at last the madness subsided. From that day forward Quetzalcoatl ruled as Quetzalcoatl Victorious, Lord of Lords, God of Gods. And Huitzilipotchli and his sister, Coyolxauhqui shared the island of Atzi. Hutizlipotchli slept there during the night and Coyolxauhqui during the day. And thus Quetzalcoatl Victorious ended the suffering of man-kind by ending the great sacrifices.