Well, perhaps in the fanfiction, Naruto is cursed with immortality as a form of punishment. He initially struggles with it, feeling isolated. But then he uses his eternal life to learn every jutsu in the ninja world and becomes an all - powerful being, using his power to protect the Hidden Leaf for all time. He might also start to mentor generations of ninjas, passing on his vast knowledge.
In some 'naruto becomes immortal fanfiction', Naruto could be given immortality by a powerful sage. This new - found immortality makes him a target for various ninja clans who want to study or use his immortality for their own gains. Naruto has to fight against them while also trying to understand the true meaning of his immortality. He may even travel the world to find others like him or to find a way to reverse it if he decides he doesn't want it anymore.
One possible plotline could be that Naruto discovers a hidden jutsu or artifact that grants him immortality. He then has to deal with the consequences of living forever, like seeing his friends and loved ones age and die while he remains the same. Another could be that an enemy tries to steal his immortality, leading to a great battle.
One possible plotline could be that Naruto is constantly rejected by the village he is trying to protect. This betrayal and lack of acceptance could gradually turn him dark. For example, if the villagers start to blame him for every bad thing that happens, even when it's not his fault. Another plotline might involve Naruto losing someone very close to him, like Sasuke, in a way that he blames the shinobi world for. This could lead to him deciding to take revenge on the world and turn to darker methods of achieving his goals. Maybe he starts to use forbidden jutsu without hesitation, seeing it as a means to an end.
One possible plotline could be that Naruto is somehow transported to a world where sorcery is the main power source. He then has to learn to become a sorceress to survive and find his way back home.
Another plot could be that Naruto is tricked into believing a false narrative about the ninja world. Similar to how Obito was manipulated by Madara's lies. He then starts to act in ways that are contrary to his usual self. He might target the other villages, thinking he is doing the right thing for some grand, but misconstrued reason. This would lead to him being at odds with his former friends, who would be desperate to bring the old Naruto back.
A plotline could involve Hermione being magically influenced by a charm that is meant to be a joke but goes wrong. As she becomes more like a 'bimbo', she starts to interact with her friends in different ways. Ron might be initially confused and Harry could be worried. But as the story progresses, Hermione uses her new - found different perspective to solve a mystery in Hogwarts that no one else could because she looks at things from an unexpected angle.
One possible plotline could be that Harry discovers a hidden pirate ship in the Forbidden Forest. He then decides to join the crew and learns the ways of piracy. Another could be that he is magically transported to a pirate world and has to adapt to survive as a pirate.
One possible plotline could be that Ash is betrayed by his friends. This heartbreak and sense of abandonment turns him evil. He then starts using his Pokémon in cruel ways to seek revenge on those who wronged him.
One possible plotline could be Izuku adjusting to her new gender identity while still trying to pursue her dream of being a hero. She might face different challenges and prejudices in a male - dominated hero world as a girl. For example, some male characters might underestimate her at first but she proves them wrong with her skills and determination.
Another plotline could be that Naruto travels to the future in his fox form. In the future, Konoha is in ruins. He then has to figure out what led to this disaster using his fox - enhanced intuition and time - travel knowledge. He could then go back to his own time and take steps to prevent the events that led to the future's destruction. This would involve him facing new enemies and making tough decisions along the way.
In some plotlines, Naruto might teach the X - Men some of his ninja techniques as a godlike or immortal being. This could help the X - Men in their battles. There could also be a love interest story where Naruto, with his unique powers, catches the eye of a certain X - Men character. His immortality could bring up questions about his place in the X - Men universe and how he'll age or not age compared to the others. Additionally, there could be a plot where Naruto has to hide his true power level from some in the X - Men world who might fear or want to exploit his godlike or immortal abilities.
One possible plotline could be Naruto's struggle to adapt to the physical and social changes of becoming Naruko. He might face new challenges in how others perceive him/her, like dealing with different expectations in the ninja world. Another could be exploring new relationships, as Naruko might interact differently with characters like Sasuke or Sakura.