In an 'immortal naruto x harry potter fanfiction', Naruto's immortality might be a result of some powerful sealing jutsu gone wrong or right. He arrives in the wizarding world and is initially confused by the different rules of magic. But he quickly adapts. He could form an alliance with Harry Potter. Together, they could explore the similarities and differences between ninjutsu and magic. For example, Naruto's shadow clone jutsu could be compared to the wizard's duplication spells. They could then use their combined skills to protect both the ninja world and the wizarding world from threats that are starting to cross over between the two realms.
One idea could be that the Hogwarts students are visited by Naruto and his friends. Naruto could show off his ninja skills, like the Shadow Clone Jutsu, which would amaze the wizards. The wizards, in turn, could introduce Naruto to magic like the Patronus Charm. Another plot could involve a common enemy that requires both the power of ninjutsu and magic to defeat. For example, a dark wizard who has also acquired some dark ninja arts.
One idea could be that Naruto is somehow transported to the wizarding world. He might attend Hogwarts and use his ninja skills in the wizarding duels. His chakra could be seen as a unique form of magic there.
In 'immortal harry potter rwby fanfiction', a great plot could be about Harry being the key to unlocking an ancient power in Remnant. Since he's immortal, he has had more time to study magic and ancient lore. He discovers that there are hidden magical energies in Remnant that are similar to those in the wizarding world. With the help of the RWBY gang, he tries to harness this power to defeat Salem once and for all. This would involve a lot of exploration of both the magical and non - magical aspects of Remnant, and the RWBY characters would be learning a great deal from Harry about magic and its potential uses.
Maybe Alucard is a time - traveler who accidentally ends up in the era of Harry Potter. He initially has his own agenda but gets involved in the fight against Voldemort. His unique powers, which are very different from the magic in the wizarding world, make him both an asset and a mystery. Harry and his friends are both fascinated and a bit afraid of him. Alucard could also introduce a new type of magic or power that the wizards have never seen before, which could change the balance of power in the war against the Dark Lord.
One idea could be that a character from Harry Potter, like Hermione, accidentally gets transported to Storybrooke. She could use her magic knowledge to help the residents solve a mystery that has been plaguing the town. Maybe it's a spell that has gone wrong and is causing strange things to happen, and her logical thinking and spell - casting skills would be very useful.
One idea could be that Slenderman somehow enters the wizarding world of Harry Potter. Maybe he's drawn by the powerful magic there. He could start causing strange disappearances in the Forbidden Forest, and Harry and his friends have to figure out how to stop this new, otherworldly threat using both their magic skills and their knowledge of the wizarding world's secrets.
One plot idea could be that a Kitsune disguises itself as a student at Hogwarts to learn more about human magic. It could get involved in Harry's adventures and use its Kitsune abilities, like shape - shifting or illusion - casting, to help or sometimes cause trouble. Another idea is that a Kitsune is a guardian spirit of an ancient magical place near Hogwarts, and Harry discovers it during one of his explorations. The Kitsune then becomes an ally or a guide for Harry in uncovering secrets about the wizarding world.
One idea could be that Shikamaru, with his strategic mind, gets transported to the wizarding world of Harry Potter. He could use his intelligence to help Harry and his friends in their battles against Voldemort. For example, he might come up with unique battle plans that the wizards hadn't considered before, like using the environment in Hogwarts in unexpected ways during duels.
Well, a plot could be Loki disguising himself as a Hogwarts student. He gets involved in the house rivalries and eventually meets Harry. They start off as adversaries but then realize they both have a common goal of protecting the wizarding world from a hidden danger. For example, an ancient evil that is about to be awakened. Loki could use his Asgardian knowledge and Harry his wizard skills to defeat it. Also, Loki could be interested in the magic of the wizarding world and want to learn more, leading to some humorous and interesting interactions with the Hogwarts professors.
Another plot could involve a crossover of villains. A dark wizard from the Harry Potter universe teams up with a criminal that the NCIS has been chasing. Harry Potter and the NCIS agents then have to join forces to stop this unholy alliance. They would need to combine their skills, with the wizards using magic and the agents using their detective and combat skills.