One way it could work is if Naruto's immortality was due to some sort of chakra - based magic. In the Star Wars universe, the Force has many mysterious aspects. Maybe Naruto's chakra could be seen as a form of the Force. His immortality could be related to his strong life force, similar to how some characters in Star Wars seem to have an indomitable will to live that keeps them alive through tough situations.
His role could be that of a teacher. Naruto has a lot of knowledge and experience from his own world. In the Star Wars fanfic, he could teach both Jedi and Sith about different ways of thinking and using power. Since he's immortal, he can pass on this knowledge over a long period of time.
If Naruto were immortal in a Star Wars fanfiction, the story would have a whole new flavor. Naruto's immortality would make him a long - term player in the galactic politics. He could potentially outlive many of the major players in the Star Wars universe. His ability to learn and adapt, which was evident in the Naruto series, would help him master Jedi or Sith techniques. This could lead to him being a sort of wildcard, not fully on the side of the Jedi or Sith, but rather trying to find his own path to peace in the galaxy.
He might use his ninja skills to become a great warrior. Naruto's speed and strength, along with his immortality, would make him a formidable opponent. He could take on Sith Lords or help the Jedi in battles.
One idea could be that Naruto is somehow transported to the Star Wars universe during the Clone Wars. He could use his ninja skills, like his shadow clone jutsu, in unique ways on the battlefields. For example, his clones could be used to create diversions while the Jedi try to outmaneuver the Separatist droids.
In this fanfiction, Naruto and Yugito could be reimagined as characters within the Star Wars Clone Wars setting. Naruto's chakra could be equated to the Force in some ways. They could find themselves in the middle of the Clone Wars, with Naruto's determination and Yugito's strength making them valuable allies. For example, Naruto might use his shadow clone jutsu to confuse the battle droids, while Yugito's cat - like abilities give her an edge in stealth and combat.
Perhaps a fanfiction where some of the Naruto characters are actually clones themselves, like in The Clone Wars. Naruto could be a special clone created with a combination of chakra and the Force. His purpose could be to bring peace between the two universes. Hinata could be a healer in this new world, using her gentle nature and Byakugan to sense injuries and use the Force to heal them. This would mix the two universes in a unique way and create a lot of new storylines.
Naruto's godlike presence in Star Wars fanfiction would bring chaos and change. He would be able to move at incredible speeds and have strength beyond what most Star Wars characters could fathom. His ability to transform, like into his Nine - Tails form, would be like nothing they've ever seen. This could either terrify the inhabitants of the Star Wars galaxy or make them revere him. In terms of the story, he could become a key figure in the fight between the light and dark side, perhaps even finding a new way to balance the two, different from what the Jedi or Sith have proposed.
One possible fanfiction could be about a Sith Lord from Star Wars ending up in the Naruto universe. Maybe he tries to use the Force to control the chakra, but finds that it's a completely different power system. He could then form an alliance with some of the villains in Naruto, like Orochimaru, who are also interested in power and dark arts.
There are some really interesting ones out there. For example, there are fanfictions that combine the ninjutsu elements from Naruto with the space battles in Star Wars Clone Wars. Some stories might focus on a character from Naruto being transported to the Star Wars universe and having to adapt to the new environment, like Naruto using his chakra in a lightsaber fight. It's a really cool concept and can lead to some very creative storytelling.