Well, in some 'naruto goes to alternate universe fanfiction' plots, Naruto might find himself in a world where all the ninja clans have merged into one big super - clan. He'd have to navigate the complex politics within this new structure. Also, there could be a plot where he enters an alternate universe where the Fourth Great Ninja War never happened, but there are new threats emerging that he has to face. And then there's the idea of a universe where Naruto's parents are alive, and he has to deal with a completely different family dynamic.
Sasuke is often a common character. Since they have such a deep relationship in the original Naruto story, it's likely they'll interact in the alternate universe too. Kakashi could also be a common one. He was Naruto's teacher, so it makes sense for him to be around in different universes. And Sakura, as part of the original team, is also likely to interact with Naruto in these fanfictions.
First, come up with a unique concept for your alternate universe. It could be something like a world where ninjas use modern technology. Then, think about how the characters will be different. For Naruto, maybe he's not an orphan or he has different abilities. Next, plan out the plot. You can start with a small change in the Naruto universe and build on it. For instance, if the Uchiha clan was never massacred, how would that change the relationships and the overall story?
In the alternate universe, Harry could meet different versions of his friends and enemies. His relationship with them would be very different. For instance, Hermione might be a Death Eater or Ron could be a powerful dark wizard. It would be a huge shock for Harry to deal with these new identities of people he thought he knew well.
One great 'alternate universe naruto fanfiction' is 'Road to Ninja: Naruto the Movie - Another Side'. It presents a very different Naruto world where characters have different personalities and roles. For example, Naruto has a family in this AU which changes his whole dynamic.
He could meet an alternate version of himself. This Naruto might have made different choices in life, like choosing not to pursue being a Hokage. It would be interesting to see how they interact.
In the alternate dimension, Naruto could find that the Akatsuki are actually the protectors of the villages. This would completely change his view of the world. He would have to re - evaluate his ideas about good and evil and decide whether to help them or oppose them depending on their true motives.
Perhaps in this alternate reality, there are no ninja villages at all. People live in a more unified world, but they face a new and powerful enemy that Naruto has to help fight. He would have to adapt his skills and learn new ways of combat that are unique to this world.
Sasuke is often very popular in Naruto AU fanfiction. His complex personality and powerful abilities make him a great character to reimagine in different universes. Naruto himself is also a common focus, as writers like to explore different versions of him.
One interesting concept could be a Naruto AU where the ninja world is a modern, high - tech society. Instead of using traditional ninja tools, they use advanced weapons and gadgets. Another could be an AU where the main characters have different elemental affinities than in the original story, which would change their combat styles and relationships.