One way for Naruto characters to become immortal in fanfiction is by delving into the secrets of the Sage of Six Paths. Maybe there is a hidden aspect of his power that can grant immortality. In Fairy Tail, characters could use powerful lost magics. There might be a long - forgotten magic spell that, when cast correctly, can make a mage immortal. They could discover this magic in an ancient, hidden library or from a very old and wise wizard.
In fanfiction, Naruto could become a strong Fairy Tail mage through a series of steps. Firstly, he needs to adapt his ninja mindset to the magical world. This means learning about the magical energy sources and how they differ from chakra. He could then use his experience in combat and strategy from being a ninja. For example, his ability to analyze his opponents quickly can be applied in battles against other mages. Next, he should explore his own potential in magic. Maybe he has an affinity for a certain type of magic that he can develop further. And finally, he can form strong bonds with other Fairy Tail mages, which would not only give him emotional support but also opportunities to learn new magic and techniques.
First, you need to come up with a solid plot idea. Think about how the Naruto universe, the concept of immortality, and Fairy Tail elements can interact. For example, you could start with a character from Naruto ending up in the Fairy Tail world and discovering a way to gain immortality there. Then, plan your characters' arcs carefully, deciding how they'll change and grow throughout the story.
Naruto's chakra could be seen as a form of magic in the Fairy Tail world. His ability to use Shadow Clones, for instance, could be combined with a Fairy Tail mage's illusion magic. He could create dozens of clones that are also capable of casting illusions, confusing enemies. His Rasengan could be enhanced with different types of magic, like wind magic to make it even more powerful and destructive.
Well, in such a fanfiction, the storyline might develop with Naruto's immortality bringing new challenges to the Fairy Tail world. Maybe he has to deal with dark guilds in a different way because he can't be killed easily. His ninja skills could also blend with the magic in Fairy Tail, creating unique combat styles.
One possible storyline is Naruto joining Fairy Tail and using his immortality to protect the guild from powerful enemies. He could take on dangerous missions without the fear of death. Another could be that he tries to find a way to reverse his immortality because he misses the normal cycle of life and death. Or perhaps he becomes a mentor to the younger Fairy Tail members, teaching them his ninja wisdom along with his unique immortality - related skills.
Natsu is often a very popular character. His already strong and fiery personality can be even more interesting when combined with immortality. He could continue his battles and adventures without the fear of death. Another popular one might be Erza. Her discipline and strength would be enhanced in an immortal setting as she could keep on protecting the guild for eternity.
There are likely fanfictions where Naruto's immortality in the Fairy Tail setting gives him unique powers. For example, he might be able to combine his ninja skills with Fairy Tail magic in ways that no one else can. His immortality could also mean he has an infinite amount of time to master different types of magic, making him an extremely powerful and feared figure in the Fairy Tail world.
In fanfiction, a writer can make Naruto part of Fairy Tail fanfiction by creating a crossover scenario. For example, they could write that Naruto somehow ends up in the Fairy Tail world through a magical portal. Then he might use his ninja skills in the Fairy Tail universe, like fighting alongside the wizards of Fairy Tail against common enemies.
Well, in some fanfictions, the immortality aspect might lead to really cool plotlines. Imagine Naruto characters like Sasuke or Kakashi becoming immortal and interacting with Fairy Tail's immortal characters like Zeref. They could exchange knowledge about their different forms of power and how to control their newfound immortality. Also, the guilds in Fairy Tail and the ninja villages in Naruto could form alliances based on this new shared situation of having immortal members.
There's also 'Immortal Bonds in Naruto - Fairy Tail'. This fanfic focuses on the idea of how characters from Naruto and Fairy Tail form unbreakable bonds while dealing with a threat that can only be faced with the combined powers of immortality, ninjutsu and magic. It delves deep into the character development of both universes' characters.