One idea could be a crossover where Pokemon trainers visit the Avatar world. They could learn bending techniques and use their Pokemon in unique ways to help the Avatar in a great battle. For example, a Pikachu could use its electricity to enhance a waterbender's attack.
Another plot could involve an Avatar who has the ability to communicate with Pokemon. This Avatar travels between the Pokemon world and their own world, trying to bring peace between the two realms. They might face challenges like Pokemon poachers in the Avatar world or warring factions in the Pokemon world.
One idea could be the main character being reborn as a Pikachu and having to navigate the world with its electric powers while making friends with other pokemon. Another could be being reborn as a Eevee and having the unique ability to evolve into any form at will, which causes both envy and admiration among other pokemon. Maybe the reborn pokemon has memories of being a human and uses that knowledge to outwit trainers and other threats.
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.
One idea could be that the OC is a powerful bender who saves a group of characters of different genders from a great danger. In return, they all develop feelings for the OC and form a harem. For example, if the OC is a water bender, they might save some earth benders and fire benders from a group of bandits. Another idea is that the OC has a special ability that is needed to save the Avatar world, and as they travel around recruiting help, different characters join them and fall in love.
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.
One idea could be an avatar from a different dimension arriving in the High School DxD world and having to adjust to the unique social and power dynamics there. For example, an avatar with ice - based powers might struggle with the more demonic and devilish heat - based powers in the High School DxD universe.
One plot idea could be Jake Sully having to face a new, unknown threat in Pandora that is not related to the RDA. Maybe a strange disease starts affecting the Na'vi and Jake has to go on a journey to find a cure. Another could be Jake having to deal with a power struggle within the Na'vi clans. A third idea is that Jake discovers a long - lost Na'vi tribe that has a completely different culture and he has to figure out how to integrate them with the rest of the Na'vi.
One idea could be that the Avatar travels back to the time when the Air Nomads were first attacked. They could try to prevent the initial destruction and save many of their lives. This would change the entire course of history in the Avatar universe, as the Air Nomads played a crucial role in the balance of the world.
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.
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.
A cool plot might be an avatar from a different world being brought into the Game of Thrones world and having to adapt to its politics and power struggles. This avatar could have unique abilities that make them a valuable asset or a feared enemy. For example, they could have the ability to read minds, which would give them an edge in the cut - throat world of Westerosi politics. They could either side with a noble house or try to create their own power base.