Perhaps in the fanfic, Dark Naruto and Azula are both outcasts in their respective worlds. They meet by chance and immediately recognize the darkness within each other. They decide to create their own little empire, away from the judgment of others. They use their combined powers to build a fortress and gather followers who are also disillusioned with their original worlds. They then plot to take over both the Naruto and Avatar worlds.
Another storyline could involve Dark Naruto being transported to Azula's world. At first, they are at odds as they misunderstand each other's motives. But as time passes, they realize they share a common goal of power and control. They start to train together, with Naruto teaching Azula some of his more devious ninja tactics and Azula showing Naruto the finer points of firebending. Eventually, they rule over a part of the Avatar world together.
In a more complex interaction, they could end up influencing each other. Dark Naruto's darker nature could make Azula even more ruthless in her pursuit of power. Meanwhile, Azula's strong sense of pride and leadership could make Naruto more confident in his own abilities. Their relationship could be a very volatile and dynamic one, constantly shifting between alliance and rivalry depending on the circumstances in the fanfic.
One possible storyline could be that Naruto struggles to control this dark chakra. He might accidentally harm his friends and then have to go on a journey to find a way to suppress or purify it. For example, he could seek out ancient jutsu or visit reclusive sages.
One possible storyline could be that Naruto is betrayed by those he trusts most in the village. This heartbreak and sense of abandonment could lead him down a dark path. He might start to question the values he was taught and use his power in more self - serving and ruthless ways.
A good storyline could involve Azula's redemption through her interactions with Naruto. Naruto, with his belief in the good in people, could try to help Azula overcome her dark past. Maybe they start off as enemies, but as they face challenges together, Azula begins to change. For example, they could be on a mission to stop a powerful dark wizard who is trying to take over both the Fire Nation and the Hidden Leaf Village.
One possible storyline could be Naruto being possessed by a Devilman - like entity. His friends then have to find a way to free him while dealing with the new, more dangerous Naruto. Another could be Naruto willingly accepting Devilman - like powers to defeat a greater threat, but then struggling to control them.
One possible storyline could be that Naruto is kidnapped by a rogue ninja group who wants to use his power for their own evil deeds. They might try to force him to reveal the secrets of his special jutsu. Another could be that he is kidnapped by a mysterious organization that believes he is the key to a long - lost prophecy. They hold him captive while they try to figure out how to use him to fulfill the prophecy. A third storyline could be that Naruto is kidnapped by a group of enemy ninjas from another village who see him as a threat to their plans for domination.
One possible storyline could be Naruto running away from the village. Since his family ignores him, he might feel like there's no place for him there. He could then go on a journey to find a place where he is accepted. Another storyline could be Naruto becoming a sort of lone wolf within the village. He trains in secret, away from everyone, and emerges as a powerful but mysterious figure. He might also start to form alliances with outcasts in the village who also feel ignored.
One possible storyline could be Naruto discovers his true heritage early on and has to deal with the pressure of living up to Hagoromo's name. He might struggle with new expectations from the village and his friends.
A possible storyline is that Naruto accidentally stumbles upon a hidden dojo where Rokushiki is practiced. The dojo master, seeing Naruto's potential, takes him in as a student. As he learns Rokushiki, he has to face the challenges of combining it with his ninja skills. He might also face opposition from some of the other students who are jealous of his natural talent. This could lead to various conflicts and growth for Naruto's character within the fanfic.
One possible storyline could be that Tracer is on a mission in her Overwatch world and gets sucked into a portal that leads her to the Naruto universe. There, she meets Naruto and his friends, and they initially don't trust each other. But as they face common enemies, like some rogue ninjas who are after Tracer's technology, they start to work together and form a bond.