In a more complex scenario, a Naruto character who has a dark side within them, like Sasuke at some points, could be influenced by the essence of a Sith Warrior. This influence could cause them to make different choices in their journey, and the fanfiction could explore how the Naruto world would react to this new, darker version of the character.
One idea could be a crossover where a Naruto character somehow gets transported to the Star Wars universe and is mistaken for a potential Sith Warrior. They have to navigate the dark side teachings while also trying to find a way back home.
One idea could be a story where a Sith Assassin somehow gets transported to the Harry Potter universe. Maybe they initially see it as a strange and weak world compared to their own, but then they discover the unique magic there. They could try to use their Sith powers to dominate, but find that the magic of Hogwarts and its defenders are not so easy to overcome.
One idea could be a crossover where a powerful Sith Sorcerer somehow finds his way into the Harry Potter universe. Maybe he's on a quest for a unique magical artifact that only exists in the wizarding world. He could start causing chaos, and the Hogwarts students have to figure out a way to stop him using both their magic and their knowledge of the wizarding world's secrets.
One idea could be that a Harry Potter character, like Harry himself, discovers an ancient Aztec magic during his travels. Maybe he stumbles upon an Aztec temple hidden in the Forbidden Forest. This new magic could have unique powers that he has to learn to control and incorporate into his existing magical abilities.
Maybe there's a crossover where Voldemort teams up with a Sith Lord. They could share their knowledge of dark magic and the dark side of the Force. This would create a powerful and terrifying alliance. The heroes from both universes, like Harry Potter and the Jedi, would then have to join forces to stop them. They would face many challenges as they try to understand and combat the combined powers of their enemies.
One idea could be to have characters from Naruto end up in the world of Danmachi. For example, Naruto himself could find his way into the dungeon and his ninja skills would be put to the test against the dungeon monsters. His shadow clone jutsu could be used in interesting ways, like sending clones into different dungeon levels to scout or fight. Another idea is to have the concept of chakra introduced into the Danmachi world. This could change the way adventurers fight and level up. Maybe some of the Naruto characters could train the Danmachi adventurers in new combat techniques.
One idea could be a crossover where Naruto is somehow transported to the Star Wars universe and meets Padme. Maybe he uses his ninja skills to protect her from the Sith.
Another concept is that Naruto is sent to Middle - earth. There, he could use his ninja skills and chakra powers. He and Gandalf could team up to fight Sauron. Naruto's ability to make friends and inspire others would be really useful in uniting the different races of Middle - earth against the common enemy.
A more complex idea is that the Matrix is used to create a virtual training ground for the shinobi. They enter the Matrix to practice their skills in a more controlled environment. However, they soon realize that there are some dark secrets within the Matrix, and Naruto has to lead the way to uncover the truth and free those who are trapped inside.
Another possibility is that Naruto visits the Townsville, the city where the PPG live. He might be confused by the modern technology there compared to his own world. The PPG could teach him about it while he shows them some of his ninja skills like tree - climbing and water - walking.
A third idea could be a story where Naruto's clones are mistaken for some kind of superpower by the Thundermans. Max might be intrigued and try to figure out how to do it himself. Meanwhile, the Thundermans could teach Naruto about modern technology which he has never seen in his own world. This could lead to some really interesting and comical situations as they try to understand each other's worlds.