The villain turned hero trope is used exceptionally well in Avatar: The Last Airbender through the character Zuko. Many cartoons and anime have seen villains with a change of heart in the story, but Zuko's change is a bit more realistic than most. The only downside is how long it takes to actually happen.
Throughout the series, there were plenty of times Zuko could have stopped chasing the Avatar and joined forces with him but he didn't, and for the most part for some incredibly deep and understandable reasons. However, after a while, it just seems like the young Prince is just stalling his inevitable destiny.
10 Zuko Saved By Aang After Rescuing Him From Zhau
When Aang is held captive by Admiral Zhao, a masked warrior named The Blue Spirit comes to his aid. As they escape together, The Blue Spirit is knocked down, his mask falling off revealing he is none other than Prince Zuko. Unable to leave him behind, Aang rescues Zuko.
When Zuko wakes up, Aang asks if they could ever be friends, but Zuko responds with a violent force of fire at the boy. Zuko only saved Aang because he wants the glory of capturing the Avatar for himself, and at the time friendship is the farthest objective in his mind.
9 Zuko Saved Again By Aang In The Northern Water Tribe
During the siege of the Northern Water Tribe, Zuko almost succeeds at capturing Aang, but a blizzard stops him in his tracks. At this point, they are enemies with a total disdain for each other, so it's no surprise that neither would want to join forces. After Katara knocks Zuko unconscious and the gang prepares to fly away on Appa, Aang can't bear to leave Zuko to freeze to death.
Zuko could have taken the act of kindness as a sign that maybe he'd be better off working with them, but it was far too soon for the Prince who was still holding on to the hope of restoring his relationship with his father.
8 Immediately After He And Iroh Become Wanted Men
Zuko and Iroh are found by Zuko's sister Azula who tells them that their father wants Zuko back home. Iroh is suspicious of the claim, but Zuko is elated that his father wants him back. He learns the hard way is that it's all a lie to capture the two as prisoners.
In the heat of battle, Azula rubs it in Zuko's face that their father considers him a failure. After he and Iroh run away from her clutches, they become wanted men of the Fire Nation, cutting ties from the family. This moment would've been a great time to join the heroes, but instead, the two of them choose to huff it alone.
7 Zuko Rejects Team Avatar After Iroh Is Hurt By Azula
In a group stand-off against Azula, Zuko momentarily works with Aang and his friends to defeat her. When Azula tricks them to lower their guard pretending to surrender, she strikes Iroh causing Zuko great distress. Azula manages to escape, and Katara runs to Zuko to offer her healing to the wounded Iroh, not allowing Katara to explain how she can help, Zuko shouts for them to leave and the heroes choose to abide.
If Zuko was a little more level-headed at that moment and more importantly was willing to accept the help of others, he could've started his bond with Team Avatar a lot sooner. His anger is what stood in the way.
6 Zuko Finds Notice Of Aang's Whereabouts In Ba Sing Se
As Zuko and Iroh manage to start a new life in Ba Sing Se, Aang is on the search for Appa, who was stolen from him. Flying on his glider, Aang sends out pamphlets of the missing bison all across the city, not realizing that Zuko is just below and now knows he's there.
Still clinging to the idea that he has to capture the Avatar, Zuko runs to his Uncle to announce his revelation of him being so close. At the very least, this could've been a sign to Zuko that he and Aang are meant to work together, not be enemies, but Zuko just couldn't move on from the past.
5 Zuko Finds Appa Before Team Avatar
In Ba Sing Se, Zuko interrogates a Dai Li agent as The Blue Spirit in order to locate Aang's bison. He forces information out of the agent and heads to Lake Laogai where Team Avatar is also heading. Zuko finds Appa first and appears to have a scheme to use the bison, but before he can act Iroh appears from the shadow revealing that he's known about Zuko's identity as The Blue Spirit for some time.
Iroh pleads with his nephew to rethink his destiny, and for once Zuko listens and chooses to retreat with his Uncle, avoiding Aang and his friends once more. Iroh and Zuko might have been focused on starting fresh, but joining Team Avatar surely would've been refreshing at this moment.
4 Zuko's Heart To Heart Moment With Katara
With both of them captured by Azula, Zuko and Katara had some quality time to come to an understanding. Katara finally has a chance to offer Zuko help by healing his scar, a constant reminder of all the pain he's gone through. Zuko's recent metamorphosis is reflected in this moment; he's not only calm and opening up, but he also appears ready to accept the help of another.
Before they're even rescued, this is a chance for Zuko to declare himself an ally. Most likely the troubled teen is still having a hard time choosing his place in the world, but with so many signs that he should align himself with the heroes, it's almost a surprise that he doesn't here.
3 Zuko Is Given More Life-changing Advice From His Uncle
Although Zuko doesn't join Team Avatar after talking with Katara, perhaps he just needed another push from Iroh. When Aang and his Uncle find them, Iroh talks to Zuko about how it's time he chooses the path of good, a huge hint that Zuko should join the Avatar. He doesn't have a chance to respond before they're attacked by Azula and the Dai Li.
With all the changes he's gone through and all the good he's received just from his short-lived moments with Aang and his friends, it seems obvious to the audience what Zuko's next move should be, but Zuko himself feels otherwise. Even after all the abuse from his sister, Zuko joins her side in battle, nearly killing Aang.
2 Upon The Realization That He's Avatar Roku's Great Grandson
After returning home to the Fire Nation, Zuko is led to hidden records about the former Avatar Roku and his friendship with former Firelord Sozin. He reads all about their lives and how Sozin forsakes his friendship with Roku in order to spread the Fire Nation's influence and take over the world. The heartbreaking story only angers Zuko because he doesn't see how it applies to him and his destiny.
When he takes out his frustrations on his imprisoned uncle, Iroh responds calmly and explains that the connection is that Avatar Roku is Zuko's maternal great-grandfather and the family ties are what is conflicting Zuko. Sadly, the revelation isn't enough to convince Zuko that he must join forces with Aang.
1 Right After The Fire Nation War Meeting
Zuko's first War meeting since his banishment doesn't exactly go as he wanted it to. Although he admits everything turned out well with him being "the perfect prince, the son [his] father wanted" he's disappointed that he did so by not being his true self.
Again, perhaps Zuko needed the few days to come to the conclusion of leaving the Fire Nation to join Team Avatar, but after everything he's gone through this could have been a moment for him to leave right away. Instead, Zuko waited for the day of the solar eclipse to confront his father, taking advantage of the fact that he was without his bending.