Eyre (pronounced E-rye) was Macai's father and a General in the Military of the Fire Nation. Eyre went to school with Ozai and Iroh when he was a younger man. He often kept to himself and didn't get involved in other people's problems. Eyre strongly valued his family name and wanted his son to be a great leader like himself. Eyre saw his son as an extension of himself and his legacy. Eyre was a part-time author and used his influence to sell several military guidebooks.
Yosari
Eyre married Yosari when he was eighteen years old. It was an arranged marriage by her family. At the time, Yosari believed Eyre was a kind and intelligent individual. She was right that he was intelligent, but she did not fully comprehend his cold nature until after marrying him. Yosari liked another man named Hoken, but she never furthered her relationship with him because her family ay Eyre as a good candidate for marriage.
Eyre occasionally showed loving qualities as a husband, but ultimately put his position as a General over his family. This disgusted Yosari and Yosari vowed to now be the same way with her son Macai. At some point in the marriage, Yosari began to question her decision of marrying Eyre. She felt pressured and wanted an immediate way to leave her home. She had to deal with an abusive father who harmed her mother several times. Yosari concluded that she had made her foolish decisions because she was simply too young for the responsibilities that hit her.
Eyre appreciated Yosari as a wife for her beauty, class, and loyalty. However, Eyre believed that Yosari was a stubborn and troublesome wife at times.
The General's Mentality
Eyre was not like all Fire Nation Generals. He believed that if losses were too great, that his troopers should fall back from battle. At one point, this earned him the scorn of Ozai during a heated battle when Eyre ordered his troops to pull back. Eyre was also disgusted by the actions of certain Fire Nation leaders like Zhao who needlessly sacrificed several of their soldiers with overly aggressive and reckless tactics. Despite this, Eyre did not openly challenge him due to fear of losing his position, Instead, Eyre covertly undermined his rivals and promoted other ways of thinking in several of the books he wrote.
Eyre often treated his soldiers decently. He didn't go out of his way to help them beyond what was reasonable because he believed that was weak and impractical. However, he was not unnecessarily harsh either because he believed that was foolish. Despite this fairness, Eyre would severely punish any officers who showed significant incompetence. Eyre also commanded his officers to punish soldiers who constantly failed, or they would suffer his wrath. Eyre was a feared General within his unit and to many other units as well.
His unit was fairly feared for the advanced tactics they displayed in combat. While the officers under his command were many of the best tacticians in the Fire Nation, Eyre himself was a great strategist. Many considered Eyre to be a better strategist than both Iroh and Ozai but he did most of his planning behind the scenes. Ozai also took credit from some of Eyre's schemes.

Abilities
Eyre was a skilled combatant and firebending master. He bent orange fire that was a larger width than that of most benders. His flames were a bit larger than Zuko's during book 3 of ATLA. Eyre had a more defensive style, but it was not as defensive as Azula's. Eyre described his style as sixty percent defensive and forty percent offensive. Unlike Azula, Eyre had more of a traditional defensive style. While some benders like Azula are counter-offensive fighters who are known for actively attacking their enemies right after they attack (in addition to traditional defense); Eyre simply waited for his enemies to become vulnerable or tire.
Eyre was considered one of the top ten firebenders of his time (pre-ATLA era). However, he was not as skilled as Jeong Jeong, Iroh, or Ozai. With what he lacked in sheer skill, Eyre made up for with his strategy. Even so, his strategy would later become second to Azula's who learned at a faster rate than he did.
Personality
Eyre was cold and indifferent about many things. He was calculating and studied the cultures of his enemies. Eyre made a book that described how to break the will and spirit of his enemies. His tactics included framing enemy leaders, buying out local factions, putting puppet leaders in charge of conquered territories, and playing enemies against each other. Eyre used his manipulation tactics to keep several annexed Earth Kingdom territories in line and to pave the way for several Fire Nation invasions that were successful.
Eyre did not always agree with Firelord Ozai, but he never challenged him because he believed that wasn't his place as a General. Eyre believed that everyone needed to play their part in the Empire and that the ultimate gains of loyalty outweighed the costs of rebellion. Eyre was grateful for the wealth that his family had acquired by being a part of the Fire Nation and the wealth that his nation had obtained by Imperializing other territories. For this reason, Eyre felt his actions were justified. Eyre once told his son, "Sometimes you have to do bad things in order to get the best results. Those who complain are always at the bottom of the food chain because they do not understand this basic rule of life."
Eyre approved of his son Macai dating Princess Azula because he was her as a tool to help advance his family name. However, he was also cautious of Azula and believed she was "unstable and dangerous". However, he believed that Macai dating her was a worth the risk.