One popular plot idea is a crossover where Naruto characters end up in the Avatar world. For example, Naruto could learn bending techniques and use his ninja skills in combination with them. Another idea is a story where the Avatar has to learn from Naruto's way of never giving up. Also, a plot could involve the Akatsuki trying to take over the Avatar world for its resources.
In some Avatar Naruto fanfiction, a common plot is about a character from Naruto going on a journey in the Avatar world to find a way to bring back a lost friend or power. For instance, Sakura might travel to different nations in the Avatar world in search of a special herb that could revive someone in her own world. There could also be a plot where the Avatar and Naruto team up to fight a common enemy that threatens both their worlds, like an ancient evil that has the power to disrupt the balance of chakra and bending.
Well, some people like the idea of Naruto characters being reimagined as benders in the Avatar universe. Like Sasuke as a firebender with his Sharingan giving him an edge in controlling the flames in a unique way. Or Hinata as a waterbender, using her gentle nature to create beautiful and powerful waterbending moves. And then there are stories where the Nine - Tails in Naruto has some sort of connection to the spirit world in the Avatar setting.
In a naruto x avatar fanfiction, there could be a scenario where the Akatsuki from Naruto's world teams up with some of the villains from the Avatar world. This would force Naruto and the Avatar (whichever one it may be) to put aside their differences and form an alliance with other characters from both worlds to stop this powerful and evil coalition.
Perhaps the nine - tailed fox in Naruto and the Avatar state could have some sort of connection. In the fanfiction, the two powers could interact in unexpected ways. For example, when Naruto enters his nine - tailed fox mode, Aang's Avatar state could be affected, or vice versa. They might have to learn to control these interactions to save both their worlds from a dark force that wants to use this power connection for evil.
Well, a great plot for 'naruto crimson avatar fanfiction' could be centered around a tournament. Naruto and his friends enter a tournament where they have to use their new Crimson Avatar powers. But there's a catch - the tournament is being secretly manipulated by an old enemy who wants to steal these powers for themselves. The characters must not only compete but also figure out the enemy's plot and stop them.
Perhaps in the 'immortal naruto avatar fanfiction', Naruto's immortality is a curse at first. He has to figure out how to control it while also dealing with the political unrest in the Avatar world. He might form an alliance with the Avatar to bring peace. This would involve a lot of character development as Naruto struggles with his condition and tries to do good in a foreign land.
A really interesting plot would be if the Nine - Tailed Fox in Naruto had some sort of connection to an ancient and powerful spirit in the Avatar world. The Avatar and Naruto would have to figure out this connection and use it to either control or understand the power of the Nine - Tailed Fox better. This would involve a lot of exploration of both worlds' mythologies and powers, and also some great character interactions as Naruto and the Avatar learn from each other.
Another plot could be that Naruto is mistaken for an Avatar in the Avatar world. As he tries to clear up the misunderstanding, he gets involved in local politics and relationships. The female characters see his honesty and kindness, and gradually, a harem - like situation develops around him.
One idea could be that Naruto somehow gets transported to the Avatar world and his unique ninja skills draw the attention of multiple female characters. They might be intrigued by his determination and power, leading to a harem - like situation where they all vie for his attention.
A good plot idea could be about an Avatar who loses their bending abilities. They then have to go on a journey to regain them, facing various challenges along the way. Maybe they have to seek the help of a reclusive and powerful spirit who demands difficult tasks in return. Another idea is a story set during a time of peace in the Avatar world, but a new threat emerges from an unexpected source, like a group of non - benders who have found a way to harness dark energy. Or you could do a plot where the Avatar has to deal with a civil war within one of the bending nations, trying to bring balance and peace back.
One idea could be that the characters from Avatar: Pandora discover a portal to the Naruto universe. They are amazed by the ninja abilities and chakra system. Some Pandora characters might try to learn ninja techniques, while Naruto characters are intrigued by the unique flora and fauna of Pandora.
One idea could be Naruto having to face an ancient evil that threatens to disrupt the balance between the six paths and the avatar world. He might have to learn new jutsu inspired by the avatar elements. Another could be Naruto forming an alliance with avatar characters to fight a common foe, like a powerful dark spirit that can cross between their universes.