Approaching the causeway to Tenochtitlan:
Hernan Cortes stood tall, riding his horse forward through the thick brush near the edge of the lake—
Texcoco, that's its name—as he surveyed the Aztec capital. He had heard legends of a city that sat on the lake, but this vision trumped the rest. As he watched the last of the Tlaxcala and other Indians march forward, he began to fear his fate.
Even if we return to Spain with hundreds of tons of gold for the King, he can still have us hanged for treason. As he pondered that question, an idea came to his head. He turned to his companion and translator, Dona Marina, and asked her,
“What do these Aztecs believe in, exactly? What can we expect them to praise?”
“Don Cortes, you would rather not know.”
“Tell me”.
“They believe in a multitude of false gods, who rule the sky and earth and war. They believe that their gods need human blood and hearts to sustain themselves, or else the sun will not rise. They also believe in one god, named Quetzalcoatl. It is said that he was a pale faced feathered serpent, who departed to the East and vowed to return one day to rule over the Aztecs.”
Cortes was taken aback and horrified by the Aztecs belief in human sacrifice, but he quickly began to think of a way to take advantage of these superstitious primitives. He imagined that the feathers described might be a beard, and that a pale-face would be coming out of Europe, and did not Christ come from Bethlehem, far to the East of Mexico, and vow to return? Perhaps he could use this to his advantage...
Several days later:
Cortes was proud of his coup. He had arrested the Emperor of the Aztecs and, with this new puppet, had effectively taken control of the government. Now it was time to dissolve the power of the Aztec priesthood. He had come up with an idea to place Christ above the Empire, to knock out the Aztecs brutal heathenism and convert the savages to the worship of the One True God, the Father of Our Lord Jesus Christ.
Cortes had invited the main Aztec high priests to his residence, with the intention of having them abandon their idols. They were gathered on wooden chairs in the receiving room of his quarters, with the Emperor sitting above them.
Montezuma has been very cooperative, thought Cortes.
He can be useful later on. For now, however, Cortes was focusing on ending the worship of Huitzchilopochtli—
how did the heathens even pronounce that name?--and building up a basis for a new man on the Aztec throne.
Alvarado and Dona Marina stood to Cortes left and right. They would be useful in this demonstration.
When the last of the priests had gathered, Cortes began to put his plan into action. He spoke in a loud voice for Dona Marina to translate:
“Heathens, infidels, pagans! You are worshipers of false gods, of devils! You have been ripping the hearts out of innocent people for centuries, and God, the One True God, shall punish you for it! Jesus Christ, the Son of God, came down from heaven to cleanse us of our sins, and commanded us to preach his Word to all the people of the world. He has given us weapons and tools to aid us in our work, weapons He would have never given to your heathen scum! Your ancestors may have heard his Word, but it was forgotten, corrupted into the story of Quetzalcoatl. So I come to you with a choice. You can embrace the One True God, and the Love of Jesus Christ, His Son, under my stewardship, or you can keep to your heathen ways, and be annihilated. If my men and I are killed, then my King shall send great armies over the ocean, armies you cannot hope to defeat. You choose.”
Cortes's speech of fire and brimstone left the Aztec high priests and the Emperor stunned. Then the head of the Imperial guards stood and asked, “We have seen your soldiers. They shine like silver, but we outnumber you hundreds to one. We can stand against any army you ever send to defeat us.”
Cortes smiled, knowing that the moment of display had come. He turned to Alvarado and nodded. Alvarado pulled out his newly sharpened rapier and swung it at the legs of the the high priest's chair. The sword swiped right through at an angle, and the chair slid from its legs as the priest tumbled to the floor. Alvarado then took his pistol and fired through the decorative jaguar armor on the walls, punching a perfect hole through it as the bullet buried itself in the wall and broke through. Cortes smiled.
“These are the weapons you will face if you attempt to resist God's will. The weapons are gifts from our God. If you fight, then all you people will die.”
* * *
The Founding of a Kingdom
The next day, Montezuma appeared before the people. He officially handed over the throne to Hernan Cortes, who became Emperor Hernan. The priests that Cortes brought with him began missionary actions in Tenochtitlan, starting with the purification and blessing of the newly created Churches based in the former temples in Tenochtitlan. The Emperor retired with his family to Cortes's former quarters in Tenochtitlan, while Cortes moved into the Imperial palace.
Cortes immediately began a program of installing his Conquistador friends in positions of power throughout the Empire as advisors and magnates. The individual nobility of the Aztec nobles was not threatened. He also forged a peace with the Tlaxcalan Empire, asking it to join the nominal alliance that existed between Cortes's Tenochtitlan and the cities of Teotihuacan and Tlatelolco. In these cities, Cortes put his allies in charge as magnates in order to centralize the Imperial government. He funded using melted idols missionary action to the largest cities in the Empire.
But where was the army that the Governor of Cuba sent IOTL? When it landed, a large Imperial force was there to meet it, with Cortes and the Conquistadors at its lead. Cortes presents a gift to them, trying not to get involved in a war against the entire Kingdom of Spain. He provides a gift of gold, silver, and gems. Some went to the governor of Cuba, to pay off the ships Cortes took before leaving, plus interest and a gift of gold to the governor. Cortes also sent a large quantity of gold to the King of Spain. The King's Share is valued in the equivalent of $500 Billion in solid gold.
Following this gift, Cortes appointed one of the lesser Conquistadors to go to Spain in order to deliver the King's share of the gold. The meeting went as any meeting of an ambassador with a sovereign would have. The King of Spain accepted the gift, but he banished Cortes and all the Spanish Conquistadors who went with him, except for an ambassador who would be appointed by Cortes or his successors. He also demanded that a tribute of the equivalent of $500 Million be paid by Cortes's Empire to the Kingdom of Spain every year. The King, who was loyal to the Church in his entire being, was horrified by the descriptions of the Aztec Empire prior to the arrival of the Conquistadors. He ordered that one hundred missionaries be sent to Mexico. This missionary action, however, unwittingly introduced various Old World diseases to the Empire.
The Seeds of Christendom in America
When the missionaries arrived, they were each assigned an interpreter who would aid in the education of the Aztecs in the Roman Catholic faith. Most were sent to the major cities around Lake Texcoco and within the Tlaxcalan provinces, where they, under guard from Conquistadors with muskets, rapiers, and horses, purified the Aztec temples and ordered the idols melted down. Others were sent into the countryside, where they converted numerous serfs and slaves to the Roman Catholic Church. In 1522, the Pope ordered the creation of 3 bishoprics in Mexico, one in Tenochtitlan, the second in Tlaxcala, and the last in the port city of Veracruz.
However, while the missionaries were saving the souls of the savages, they were unwittingly poisoning their bodies with an invisible enemy. Numerous European diseases, including smallpox, flu, mumps, and other diseases common in Europe, began to spread through the Aztec population in Mexico. The first examples of smallpox were identified in Veracruz, by now also known as Ciudad de Cortes, but immediately spread throughout the empire. The plagues wiped out, in total, about 55% of the Aztec population by the time of Emperor Hernan's death in 1547. However, the missionaries and the Emperor managed a successful explanation of these plagues. Emperor Hernan I ordered in 1525 that the missionaries begin referring to the outbreak of diseases in the New World as punishment from God, and only those who truly believed in Jesus Christ would be left after the plagues swept through. Though rioting against the missionaries erupted in Teotihuacan in April of 1526, unfortunately leading to the murder and sacrifice of 4 of them, musketeers and swordsmen of the Emperor's personal guard were deployed to put down the pagan rioters. In response to this blatant rejection of the Holy Catholic Church, Emperor Hernan Cortes ordered the creation of one of the most important institutions in the transformation of the Empire from Aztec to the Nahuatl Empire: the Office of the Holy Inquisition of the New World.
The following year, on Good Friday, an important milestone in the spread of Christianity into the Americas was reached. On Good Friday, 1527, the first Priest of Aztec descent graduated from the Seminary. His Christian name was Paul. He would become an important missionary to the Pacific Coast portion of the Empire, establishing a mission to the savages.
* * *
Timeline
February, 1519: Hernan Cortes and his Conquistadors land on the Yucatan Peninsula with his men.
March, 1519: POD: Cortes refrains from claiming the land for the King, initially planning to conquer it fully and then give it as a gift to the King.
Rest of 1519:
Cortes arrests Montezuma and forces him to live as Cortes's puppet.
Following the above speech, Cortes claims authority as Emperor Hernan 1. He begins a program of Christianization. This is traditionally known to historians as the end of the Aztec Empire and the beginning of the Nahuatl Empire, so named to appeal to Tlaxcalans and other MesoAmerican tribes. The fundamental changes from the old Empire to the new were the adoption of the Roman Catholic Church (and, as a result, the end of human sacrifice and cannibalism) and the centralization of authority in Emperor Hernan 1.
Cortes meets the army that Velasquez sent to arrest him. He sends gifts of gold and averts a war which might have been disastrous for the fledgling Nahuatl Empire.
January, 1520: Emperor Hernan I's ambassador reaches the court of the King and Queen of Spain. Following the meeting, His Most Catholic Majesty King Charles, appeased by the gifts of gold and tribute, orders that 100 Franciscan missionaries be sent to the Nahuatl Empire, to multiply the current missionary action.
March, 1520: The first missionaries arrive at Veracruz. Many are sent to the the major cities to purify the large pagan temples.
March 17, 1520: Emperor Hernan I takes Dona Marina as his wife.
May 26, 1522: Their first son and heir to the throne, Martin, is born.
December, 1522: The Pope orders the creation of numerous parishes and 3 bishoprics in the Nahuatl Empire: the Bishopric of Tenochtitlan, the Bishopric of Tlaxcala, and the Archbishopric of Veracruz.
April, 1525: Emperor Hernan I, in response to the serious outbreaks of smallpox, mumps, and various other diseases, orders that the plagues be referred to as punishment from God and that they will end in purification.
April, 1526: Indians riot against the missionaries in Teotihuacan. Though the Emperor dispatched the elite Imperial guards to put down the riot, 4 missionaries were murdered, sacrificed, and eaten before help could arrive.
April 27, 1526: Official establishment of the Office of the Holy Inquisition of the New World. It was first run by an organization of 12 missionaries who would act as judges of those accused of heresy or paganism or witchcraft.
Good Friday, 1527: Father Paul graduates from the seminary and establishes the mission to the savages on the west coast. The Mission would later be called San Paulo.
* * *
(The borders of the Nahuatl Empire roughly matched Aztec borders right before Cortes landed, with the addition of the Tlaxcalans.)
BTW: This is my first real scenario like this, besides some discussion posts earlier. Just tell me what I can improve.