Character relationships are also a big part. Maybe Naruto and Korra become friends and mentors to each other. Naruto could teach Korra about his experiences with inner demons and self - improvement, while Korra could show Naruto new ways of looking at the world in terms of elemental balance.
Some Korra x Naruto fanfiction stories focus on a crossover tournament. Imagine a tournament where benders from Korra's world and ninjas from Naruto's world compete. Korra and Naruto are the representatives of their respective worlds. They start off as rivals but as they watch each other's battles, they start to understand each other's strengths. As the tournament progresses, they team up against a common enemy who is trying to disrupt the tournament for their own evil plans. This kind of fanfiction combines the action and unique abilities of both universes.
One idea could be a story where Naruto and Korra meet in a dimension where the worlds of their respective shows collide. They could team up to fight a new, powerful enemy that threatens both their universes. Another idea is a time - travel story where Korra goes back in time to the Naruto era and has to adapt to the different ninja world while also sharing her bending knowledge.
The origin of the Dark Avatar in fanfiction can also be very captivating. It could be a result of a corrupted spirit world influence, or perhaps a dark ritual gone wrong. Exploring how this new Dark Avatar came to be can add depth to the story and explain their motives and actions.
One interesting concept could be the characters from Naruto using Yugioh cards in their battles. For example, Naruto might use a card that represents his Rasengan to gain an advantage in a fight. Another concept could be the crossovers of the different power systems. The chakra in Naruto and the magic in Yugioh could be combined in unique ways in fanfiction.
One interesting concept could be the exploration of Naruto and Kyuubi's relationship beyond the typical master - spirit relationship. For example, in some fanfictions, they might develop a true friendship where they share their thoughts and feelings more openly. Another concept could be the power - sharing aspect. Naruto might gain new and unique abilities by having a deeper connection with Kyuubi. Also, some fanfictions could focus on how Kyuubi's past and its own emotions play into the story, like its regrets or its hopes for the future.
In Naruto x NCIS fanfiction, a cool concept could be a crossover mission. Imagine the NCIS team having to deal with a threat that has ties to the ninja world. The NCIS agents' forensic skills combined with the ninjas' combat and stealth abilities would make for an exciting story. For instance, Zoro from NCIS could learn some basic ninja moves from Naruto to enhance his own combat skills in a particular case.
Well, in Naruto x Nebula fanfiction, a cool idea might be that the chakra system in Naruto has some connection to the energy within a Nebula. Maybe the Sage of Six Paths' power was somehow influenced by Nebula energy in the past. Also, there could be a story where Naruto and his friends have to protect the Ninja World from a threat that comes from a Nebula, like an alien race with powers based on Nebula forces.
In RWBY x Naruto fanfiction, a cool concept is the crossover of character relationships. For instance, Ruby could befriend Naruto due to their similar positive outlooks and determination. Weiss might have an interesting dynamic with Sasuke as they both come from noble families and have a certain pride. Also, the idea of RWBY's world being opened up to the idea of ninja training academies and Naruto's world getting to know about Dust - based technology would make for some really engaging stories.
Another concept might be Naruto characters in the political intrigue of Westeros. For example, Naruto himself could be inserted into the story during a time of great conflict in the Seven Kingdoms. His ability to make friends and influence people could change the power dynamics in a completely different way compared to the original ASOIAF characters.
Perhaps the story explores how the order and precision of clockwork mechanisms interact with the chaotic and often unpredictable nature of the Naruto universe. This could create some really cool plotlines, like a villain using clockwork - based jutsu to try and control the flow of battles in a very methodical way.