The vastly rich world of Avatar: The Last Airbender is known for having characters that undergo tremendous growth. Fire Nation Prince Zuko's transformation from evil exiled father pleaser to independent and empathetic Firelord is an inspiration to watch. This change would have never occurred if it wasn't for his Uncle Iroh. He stepped in as a wise and caring father figure for Zuko when his real father, the ruthless Ozai, didn't want anything to do with him. Yet, Iroh wasn't always like this.
Much like Zuko, Iroh had a huge change of heart before viewers first encounter the lovable uncle. Before he was Uncle Iroh, he was the Dragon of the West. Older than Zuko's father Ozai and the original heir to the Firelord title, he was feared by the other nations, leading the Fire Nation army as a general. This suddenly changed during the siege of Ba Sing Se. What happened to Iroh? What made him go through such a drastic change?
Ba Sing Se is called an impenetrable city for a reason. It is considered the final city to be conquered in order to achieve total rule, and Iroh believed he would be the one to achieve this divine Fire Nation goal despite the failure of his ancestors. At first, he was successful in his siege, managing to get through Ba Sing Se's strong defenses. Then, everything changed when he received word of the death of his only son, Lu-Ten. He was killed by defending forces during the very siege that would have given Iroh total power.
The loss of his son destroyed the former Dragon of the West and affected him long after, as seen in the heartbreaking Leaves From The Vine scene. When he found out, he immediately lost all will to fight and ordered his army to retreat, giving up Ba Sing Se. His heartless brother Ozai took the opportunity to snatch the title of Firelord as Iroh mourned. Following the events of an Agni Kai against his brother, being shamed, and the death of his father, Iroh traveled the world to escape his grief and find himself again. He eventually became the loveably wise Uncle fans know and love. But what if Lu-Ten never died during the siege of Ba Sing Se? Reddit user u/comegetsomefood asks this haunting question in a recent Reddit thread.
If Lu-Ten never died, he would have absolutely gone through with conquered Ba Sing Se. The achievement in being the first general to have done so would have made him a legend, and it would have catapulted him straight to being the most feared Firelord to date. Even if Ozai tried to poison him like he did their father, Iroh's sharp wit and advanced power and would have surely foiled that plan. Although Iroh is much more calm and level-headed compared to Ozai, his prowess and devotion to the total rule of the Fire Nation made him objectively more terrifying than Ozai.
Fans know that Iroh has the capability of being calm and kind, but that front would be even more terrifying if paired with an unempathetic, conquer-driven mindset. The lack of empathy is especially showcased in Book 2, Episode 7, "Zuko Alone" wherein a flashback he is seen joking about burning Ba Sing Se to the ground, right before the siege.
His confidence in his power to lead the Fire Nation to a successful siege is obvious, and his incredible leadership and advanced bending skills would terrify the other nations for years. Zuko would have been most likely either killed off early without his Uncle to protect him or ended up just as evil as the rest of his family, and Aang would definitely fail in his efforts to restore balance.
Thankfully, it doesn't end up that way. Although a tragedy, Lu-Ten's death ensured a future of peace. What Iroh learned about being a father with Lu-Ten he passed down to Zuko along with the empathy and wisdom he found on his journey of finding himself again. Because of his love and guidance, Zuko is eventually empowered to stand up for himself and when he becomes Firelord, he is as kind and wise as his beloved uncle.