Well, it could be about Harry using his magic skills in the Elemental Nations. Maybe he'll learn new forms of magic there or make new friends with people who have elemental powers.
Sakura might be one of the characters. She has her own set of skills in the medical and combat fields. Meeting Harry could lead to exchanges of knowledge about different forms of healing and combat magic.
The plot might involve Naruto returning to discover that the elemental nations have changed a great deal in his absence. He could face challenges in terms of politics and power struggles among the different villages, and he'd have to use his skills and influence to restore balance.
It could also be that Naruto has been tricked. For instance, someone he trusts feeds him false information about the elemental nations being involved in a heinous conspiracy against him or his loved ones. This misinformation leads him to take drastic actions and start to destroy the elemental nations. Another idea is that Naruto loses control of his newfound and extremely powerful abilities. These abilities might be too much for him to handle and they end up causing destruction on a massive scale, starting with the elemental nations.
Well, it could be about a new student who has the power of the fire elemental. This student might struggle to control their power and Harry and his friends could help. Maybe they discover that the fire elemental power is related to an ancient magic that Voldemort wants to use for his evil plans.
One interesting plot idea could be Naruto having unique ways of uniting the elemental nations, like using new jutsu to show his power and gain respect. Maybe he discovers a hidden power within himself that is key to bringing peace among the nations.
Perhaps an old enemy that Naruto thought was defeated has returned, stronger than ever. This enemy could hold a grudge against Naruto and the elemental nations for past defeats and wants revenge.
Well, it could be that Harry goes to France on a secret mission. Perhaps he's following a lead on a dark wizard who has ties to France. In France, he might have to adapt to different magical customs while trying to complete his mission.
Maybe Harry goes to Canada to study magic in a hidden Canadian wizarding school. He could meet new friends and learn about different magical creatures native to Canada, like the Thunderbird.
In this fanfiction, perhaps Harry is sent to Beauxbatons as part of an exchange program. At Beauxbatons, he might face some challenges due to the different culture and magic styles. He could also get involved in a mystery related to the school's history, for example, an ancient spell hidden in the school that only he can solve with his unique perspective from Hogwarts.
The plot could involve Harry going to Harlem in search of something specific, perhaps a magical artifact if we're adding a bit of magic to the fanfic. Along the way, he meets interesting characters who help or hinder his search. He could also experience the different food and art in Harlem, which changes his perspective on life.