Well, the fanfiction could start with Harry having a strange encounter with some magic that makes him question his very identity. As a result, he chooses the name Zuko. With this new name, he could be drawn into a parallel dimension where the rules of magic are different. In this dimension, he has to use the lessons he learned as Harry Potter, but also adapt to the new identity of Zuko. He might meet characters who mistake him for someone from their world because of the name Zuko. This could lead to all sorts of adventures, like helping a group of wizards in this dimension fight against a dark force using his combined knowledge of both his old and new identities.
Hermione would probably be very confused at first. She'd try to understand the reasoning behind it and might be worried that Harry has lost his sense of self. Ron would likely make jokes about it, but also be a bit concerned. Dumbledore, on the other hand, would probably see it as another step in Harry's journey of self - discovery and would encourage him to explore what this new identity means. Voldemort might see it as a sign of weakness or a strange ploy by Harry, but would still be cautious as he doesn't fully understand the implications of this new name.
Zuko's complexity makes him so interesting in these fanfictions. He has a troubled past which has shaped him, but he is constantly evolving. His ability to show vulnerability in front of the reader is another great trait. It allows for a deeper emotional connection between him and the reader, as seen in stories where he opens up about his insecurities and fears.
In 'Ozai Hurts Zuko' fanfictions, Zuko develops by facing his inner demons. The harm from Ozai makes him re - evaluate his life. He might become more empathetic towards others who have suffered, and this changes his outlook on the world. He also gains a new sense of self - identity, separate from what his father wanted him to be.
There's a possibility that Zuko would meet his grandfather. His grandfather's actions and decisions might have influenced the path the Fire Nation took towards war. By meeting him, Zuko could try to sway his grandfather's views and change the future of the Fire Nation at its root.
Some fanfictions explore their role in rebuilding the world after the war. Zuko and Katara could be working together to restore balance between the nations. This kind of fanfiction often shows their leadership skills and how they complement each other.
Zuko's hot - headedness can be contrasted with Mako's more level - headed approach. Zuko might be quick to jump into action or get angry, while Mako thinks things through. As they interact, Zuko can start to adopt some of Mako's calmer ways, and Mako can learn to be more assertive from Zuko. This development can be shown through various adventures they have together, like facing a common enemy or solving a mystery.
Zuko can be developed by exploring his role as a leader within the context of his marriage. He may struggle to balance his duties as Fire Lord with his time for Mai. This internal conflict can show his character's depth. He could also develop new bending techniques influenced by his love for Mai. As for Mai, she can develop by getting involved in more political matters, standing by Zuko's side and using her intelligence to influence decisions. She could also start to make more friends in the palace, which would change her somewhat solitary nature.
In such a fanfiction, Hakoda might comfort Zuko by sharing his own experiences of loss and hardship. He could tell Zuko about how he coped when his tribe faced difficulties. For example, Hakoda might say that even in the darkest times, there is always a glimmer of hope. And that it's important to focus on the good that can come from difficult situations.