Maybe in the fanfic, an avatar in Discord gains the power of Naruto. This avatar then starts to cause chaos in the Discord world, using Naruto's techniques like the Rasengan. Other avatars have to figure out how to stop this rogue avatar, and they might seek help from the real Naruto in his own universe.
The Discord avatars, if they are aware of the Naruto characters' powers, would either be in awe or try to use them for their own gain. Some friendly avatars might offer to show the Naruto characters around the Discord world, explaining how things work like channels and servers. There could also be some conflict if an avatar has a more malicious intent and tries to trick the Naruto characters into doing something bad.
Well, a cool plot might involve Naruto being transported to the Avatar world. He gets mistaken for a powerful bender at first. As he tries to figure out how to get back home, he helps the Avatar and his friends in their fight against the Fire Nation. Along the way, Naruto teaches them some of his ninja skills like stealth and quick combat moves, and in return, he learns about the different types of bending. Maybe there could be a big showdown where Naruto's Rasengan combines with Aang's airbending to defeat a huge threat.
Perhaps in this 'emperor naruto avatar fanfic', Naruto is made emperor due to his heroic deeds in both worlds. As emperor, he has to deal with political intrigue. He might have to form alliances with different clans from the Naruto world and different tribes from the Avatar world. His friends from both universes would help him, like Sasuke and Aang. They could teach each other their unique skills and fight against common enemies who oppose Naruto's new rule.
Well, it could be about Naruto somehow getting the power of Asura and having to face off against a powerful enemy in a battle avatar form. Maybe he has to protect the Hidden Leaf from a new threat that only his newfound power can defeat.
Well, the plot could involve Celestia and Discord having to team up to save Equestria from a new, unknown threat. Maybe a powerful dark magic that neither of them can handle alone.
One idea could be Naruto having an encounter with a death - like entity that grants him new and dark powers. He might struggle with the morality of using these powers while still trying to protect his village.
One idea could be a story where the character with the Rinnegan avatar has to navigate a world where the rules of chakra and bending are combined. For example, they might use the Rinnegan's powers to control different elements in a way similar to how avatars control them in the Avatar world.
One possible plot could be that Naruto, with his newfound immortality, somehow gets transported to the Avatar world. He could meet Aang and learn about bending. Naruto's chakra control might help him quickly adapt to bending techniques. He could then team up with Aang to fight against a common enemy, like an ancient dark spirit that threatens both worlds.
Maybe the Avatar, in his journey to master all the elements, travels to the Naruto world. He could learn some ninja techniques and incorporate them into his fighting style. The Avatar could also teach the ninja about the power of bending, which could lead to some really unique team - up strategies among the characters.
The plot of 'naruto is the new avatar fanfiction' could be that Naruto is reincarnated as the new avatar. He wakes up in the Avatar world with no memory of his previous life as a ninja. As he discovers his new powers, he also realizes the great responsibility that comes with being the avatar. He then embarks on a journey to master all the elements and stop an evil force that is threatening to destroy the world, using his ninja - like tenacity and strategic thinking.