What could a 'Naruto has a Persona' fanfiction be about?

Yes, there are likely to be such fanfictions. The 'Naruto' and 'Persona' universes both have large followings, and fans often like to combine different popular franchises in fanfiction. You can search on fanfiction websites like Archive of Our Own or FanFiction.net to find them.

Perhaps the fanfiction focuses on the cultural clash between the two groups. The Persona 4 characters are from a small town, while the Persona 5 crew is from the big city. Their different ways of handling things and their unique Personas could lead to some interesting interactions. For example, Yu and Joker might have different leadership styles that they have to reconcile in order to succeed against the shadows.

Maybe the Velvet Room attendants from both games somehow get their worlds mixed up. Igor from Persona 5 and Margaret from Persona 4 have to work together to set things right. This leads to the characters from both games interacting. The Phantom Thieves might learn some new combat techniques from the Investigation Team and vice versa. They could then use these new skills to face a common threat that emerges from the merging of their two realities.

Maybe there's a strange distortion that merges parts of Inaba and Tokyo. The characters from both Persona 4 and Persona 5 find themselves in this strange new place. They start to notice that the Shadows in this merged world are more powerful and have new abilities. The Investigation Team and the Phantom Thieves must figure out how to adapt their Personas and strategies to fight these new threats while also dealing with the cultural differences between their two groups.

Well, it might be about how Naruto's life changes with the ketsuryugan. He could face new enemies who are interested in this new power he has. Also, his friends might react in different ways, some being worried and some being excited. And he could use the ketsuryugan to unlock new jutsu or abilities that are related to it. He might also have to deal with the origin of the ketsuryugan and any secrets that come with it. This could lead to a whole new adventure for Naruto, exploring new places and meeting new characters in the process.

It could be about Naruto finding a Teigu during one of his adventures. Maybe he discovers it in a hidden place and has to figure out how to use it to fight his enemies in the Naruto world.

Perhaps it's about Naruto being transported to the Dark Carnival universe and having to team up with some of the characters from that world to stop an even greater evil. He could bring his values of friendship and perseverance to the new setting, which would contrast with the more dark and twisted nature of the Dark Carnival.

Well, perhaps in this fanfiction, Naruto's 'green thumb' is a result of some sort of chakra - related power. He might be able to make plants grow super fast or even communicate with them. It could show Naruto in a different light, away from his usual ninja battles, as he nurtures a beautiful garden filled with all kinds of exotic plants that are useful for medicine or other things in the ninja world.

Perhaps in this fanfiction, Naruto is given White Zangetsu as a gift from a mysterious figure. With it, he discovers new powers and abilities. He might have to train hard to master it, and in the process, he could face challenges not only from his own world but also from forces that are attracted to the power of White Zangetsu. This could lead to new alliances and enemies for Naruto, completely changing the dynamics of the Naruto universe.

One common theme is the struggle between good and evil. In both Naruto and Persona 3, the characters face powerful foes that represent different aspects of evil. In fanfictions, they often team up to fight these greater evils. For example, Naruto's fight against the Akatsuki and the Persona users' battles against the Shadows can be combined in interesting ways.