Avatar: The Last Airbender turned Aang and Zuko from enemies to friends in Season 3. That friendship is made more viable when it’s revealed that Roku (Aang’s Avatar predecessor) was best friends with Fire Lord Sozin, Zuko’s great-grandfather. But Aang’s connection to Zuko may actually run even deeper than that.
In the Season 1 episode, “The Blue Spirit,” Aang mentions a mysterious Fire Nation friend named Kuzon that he had before he was frozen in ice for 100 years. According to Aang, they used to get into trouble together, and Aang uses the story to ask Zuko if they would’ve been friends had they met back then. However, unlike another of Aang's old friends, Kuzon never shows up in The Last Airbender.
However, a thoughtful new theory offers some clues as to Kuzon’s true identity. And if this is correct, it could change everything we know about Avatar: The Last Airbender.
Reddit user Obversa theorizes that Aang’s childhood friend is actually Prince Azulon, Zuko’s grandfather and Fire Lord Ozai’s father. It's important to note that the creators of The Last Airbender once stated Azulon was 95-years-old when he died and was born at the same time the Fire Nation attacked the Air Nomads. That means he couldn't have been friends with Aang as a child, but Avatar has shifted its timelines before to suit its story, so the theory still stands.
There's also a lot more evidence to suggest this mysterious Kuzon is actually Azulon.
The theorist observes that Aang was previously friends with Bumi, an Earth Kingdom prince. In Season 2, Aang reconnected with Bumi, who became King of Omashu and joined the Order of the White Lotus with Iroh, the former heir of Fire Lord Ozai. The idea is basically that since Aang was friends with high-ranking and royal members of the Earth Kingdom, it makes sense he'd also be friends with a high-ranking firebender... like the prince of the Fire Nation.
Avatar: The Last Airbender has a history of showcasing the Avatar’s friendships and connections with the Fire Nation. After all, Sozin and Avatar Roku were close friends before Sozin decided to declare war. When thinking about a potential friendship with Zuko, Aang specifically references Kuzon.
We know that Zuko's uncle Iroh was first in line to inherit the throne, and that Azulon didn't respond well to Ozai's attempts to undermine his brother. Perhaps Aang understood that Zuko was more like Azulon and Iroh than Ozai and Sozin and may have subtly attempted to make peace with Zuko early on.
The theory provides many more details to back up the claim, which is honestly quite plausible. The only major hiccup here is that Kuzon and Azulon don’t share the same name (plus the whole timeline thing). But the obvious answer here is that Aang is keeping this detail a secret from Zuko, who he doesn't trust at that point in The Last Airbender.
The Inverse Analysis — There may be many untapped mysteries that Avatar: The Last Airbender introduced and never explained. That said, it’s entirely possible that Aang didn’t mention Kuzon’s familial connection with Zuko knowing that he was on thin ice with the then-angry prince. After all, Zuko’s response to potentially forging a friendship with Aang was to scream and attack him with firebending.
Considering that very little is known about Kuzon, the fact that he’s specifically brought up with Zuko could mean more than some passing reference. It’s either that or we’re reading too much into it. Either way, the notion that Aang’s friendship with Zuko’s ancestor paved the way for a bond between him and Zuko is a nice thought.
For now, we'll leave it at that, unless Netflix's upcoming live-action Avatar: The Last Airbender decides to answer this question for us.
Avatar: The Last Airbender is currently available to watch on Netflix.