"You dare suggest I betray Iroh? My first born? Directly after the demise of his only beloved son? I think Iroh has suffered enough. But you, your punishment has scarcely begun!"
— Azulon to Ozai, after the latter demanded that Iroh be passed over as heir.
Azulon's reign was marked by an increased efficiency in the Fire Nation war machine and massive territorial conquests; his leadership in several Earth Kingdom campaigns won him great fame as a general. He was also responsible for the destruction of the Southern Water Tribe, which was nearly annihilated under his orders. Although seen as uncaring and cruel, even toward his own people, he is remembered as one of the Fire Nation's strongest and most effective leaders.
Born shortly after the beginning of the Hundred Year War, Azulon was a frightening man who demanded perfection. He was a firebending prodigy since childhood, and as prince, led the Fire Nation to victory in many glorious military campaigns, including the conquest of the Hu Xin Provinces and the Battle of Garsai. Azulon assumed the title of Fire Lord at age twenty, following the death of his father, and continued to lead his country in the War. Eventually, he married a woman named Ilah, who bore two children: Iroh, his mother's namesake, and Ozai. In his time, he was considered to be one of the best firebenders in the world and no one would dare challenge him. Despite his strong leadership, Azulon cared very little for the people of his nation and was more interested in world domination, a quality he passed down to Ozai.
Azulon secured many victories against the Earth Kingdom during his reign, expanding Fire Nation territory and increasing colonization in the continent. Under his leadership the Fire Nation continued to push the Earth Kingdom forces east toward the capital of Ba Sing Se. Early in his reign, he commissioned the Great Gates of Azulon to protect the entrance to the Fire Nation Capital.
Azulon was also responsible for the near-complete destruction of the Southern Water Tribe. Starting around 40 ASC, he began ordering attacks on the tribe's main city and villages in an attempt to disband its people. The Southern Raiders were created to carry out these attacks. Their main objective was to capture the tribe's waterbenders, who were seen as a threat to Fire Nation dominance in the region. These raids were successful; by the time of his death, Katara was the last remaining waterbender in the Southern Tribe, and the southern waterbending style was effectively extinct.
Sometime before 83 ASC, Azulon sought to arrange a proper marriage for his second son, Ozai. The Fire Sages had told Azulon that the pairing of the Avatar's granddaughter with his son would yield a bloodline of great power. Believing this prediction, Azulon began to search for the Avatar's family. Roku's descendants proved difficult to find, possibly by his own design.
Eventually the Fire Lord found the family in the small town of Hira'a in the outer Fire Nation. After securing Ursa's location, Azulon and Ozai personally traveled to the backwater village to arrange the marriage. After visiting Ursa's father, the town's magistrate, they waited for the girl's return from her theater rehearsal. Upon Ursa's arrival, Azulon warmly introduced himself and his son to his future daughter-in-law, and announced their intention to arrange a marriage. Ursa accepted the proposal, and they prepared to travel back the capital city.
However, when they departed from Hira'a, a commoner blocked their way, demanding they release Ursa. Azulon ordered his bodyguards to deal with him, but before the conflict escalated, Ursa intervened. She got Ozai to leave the man unharmed, and convinced the commoner to go home. After this event, Azulon and his family continued their journey back to the capital. Shortly afterwards, Ozai and Ursa married.
In 95 ASC, shortly after the death of Iroh's son Lu Ten, Ozai demanded that Iroh be passed over as heir, inciting his father's fury. Ozai declared Iroh was unworthy for the throne by allowing thoughts of his son's death to obstruct victory at Ba Sing Se. He claimed that the royal bloodline no longer continued through Iroh upon his son's death. Azulon was outraged at the suggestion to betray his firstborn son and Ozai's bold ambitions, ensuring he would punish his younger son. Azula, who spied on the conversation, later claimed that Ozai was ordered to kill his firstborn son, Zuko, forcing him to understand his brother's personal grief.
Ozai intended to murder his son, though his wife Ursa discovered the plan and plotted with Ozai to gain the throne while allowing Zuko to live. According to Ozai, Ursa committed "vicious, treasonous things that night." She was subsequently banished from the Fire Nation, and Azulon passed away that same night.
He received a cremation the following day, during which his many political achievements were mentioned and honored. In the process of cremation by the hands of the Fire Sages, the High Sage crowned Ozai Fire Lord as was Azulon's alleged dying wish.
Azulon was a ruthless and militaristic man, who saw power as the highest good. Regarded as a military genius, he personally commanded his army in many battles during his time as Crown Prince and Fire Lord. Fitting to his ruthless nature, he did not let the death of innocent civilians restrain his efforts in winning the War. This was exemplified when he ordered his army to destroy the whole Southern Water Tribe, attempting to commit genocide in the process.
However, Azulon originally was a warmhearted man when it came to his family. During his first meeting with Ursa, he behaved very warm and friendly, complimenting her on her beauty, even though she was the daughter of a mere magistrate. At this time he also seemed to be close to his second son Ozai. However, even the marriage ultimately aimed at winning power, as the Fire Sages had predicted that the pairing of Roku's and his own bloodline would yield powerful descendants who would ensure the Royal Family's rule for coming centuries.
Nevertheless, in his last years, Azulon changed more and more into a bitter and cruel man with little, if any, empathy, as he was willing to sacrifice his own grandson to show Ozai that he should not use Iroh's loss for his own advantages. He also grew distant toward most of his family, especially Ozai. At this time, he no longer seemed to think much of his younger son's family, as he was very angry and impatient with Zuko's failed firebending presentation. He also did not seem very impressed with Azula's advanced firebending talent, unlike many others.
However, Azulon still felt compassion for his firstborn son, Iroh. He also seemed to despise conspiracies, as he was deeply upset and outraged at Ozai's suggestion to betray Iroh by removing his position as Crown Prince.
Azulon was known to have been Fire Lord for the longest time during the Hundred Year War, for about seventy-five years as opposed to his father, Sozin, who ruled for twenty years during the War, and his son, Ozai, who ruled for five to six years during the War. He was also the second-longest known reigning Fire Lord, after his father.
Azulon ruled the Fire Nation for seventy-five years. However, the Fire Sage crowning Fire Lord Ozai during Azulon's funeral mentioned that Azulon reigned for twenty-three years.
Azulon was the only known Fire Lord not to have met an Avatar or airbender.
In his official portrait, Azulon stood on top of a turtle, an animal that lives both on land and in water, signifying his military successes over both the Earth Kingdom and the Water Tribes. He also held up two fireballs, reflecting his legendary power in firebending.