Maybe a plot where the concept of destiny in Naruto, like Naruto being the 'chosen one' to bring peace, is combined with the idea of fate in Hunter x Hunter. The characters could struggle with whether their destinies are pre - determined or if they can change them. For instance, Gon might meet Naruto and they discuss their different views on destiny and how they've each faced challenges related to it.
One interesting plot idea could be a crossover where Naruto characters enter the Hunter x Hunter world and have to adapt to its unique nen abilities. For example, Naruto might try to use his chakra in new ways to mimic nen techniques.
Maybe in this crossover, Naruto has a vision of the Traveler from Destiny. Curious, he somehow manages to cross over to the Destiny universe. There, he meets the different classes of Guardians. He could learn about their weaponry and powers and in turn, teach them about chakra. They could then work together to stop a Vex invasion that is spreading across both universes.
One idea could be that Naruto and Gon meet during a strange interdimensional rift. They initially misunderstand each other but soon realize they have a common goal of protecting their friends and worlds. Another could be that the Akatsuki and the Phantom Troupe somehow cross paths and form an uneasy alliance to achieve their own ends, which involves stealing powerful artifacts from both Naruto's world and the Hunter x Hunter world. And a third idea might be that Naruto and Killua swap places for a short time, experiencing the different power systems and cultures of each other's worlds.
Imagine if the main characters from both universes swap places. Naruto finds himself in the Gundam Seed Destiny world, having to pilot a mobile suit and fight in a war he doesn't fully understand. Meanwhile, a Gundam pilot like Kira Yamato ends up in the Naruto world, having to learn about chakra and become a ninja. They both have to adapt to their new surroundings and use their unique skills to survive. This would allow for a lot of character development as they face new challenges and make new friends (or enemies) in their respective new worlds.
One idea could be Naruto discovers a hidden realm where devil hunters operate and he has to learn their ways to save his village from a devil invasion.
One idea could be to cross Naruto with another popular anime like One Piece. Naruto characters could end up on the Grand Line, facing pirates and searching for the One Piece while using their ninja skills. Another idea is to cross it with a fantasy series like Harry Potter. Picture Naruto and his friends attending Hogwarts and learning magic alongside their ninja training. Or perhaps a crossover with the DC Universe, where Naruto characters gain superpowers similar to the DC heroes and fight against villains in a new, urban setting.
A third idea could be a crossover where some of the Destiny characters end up in the Naruto universe. They would have to learn how to use chakra and ninjutsu. The Guardians could be amazed by the different fighting styles in Naruto's world. And they could also share their knowledge of advanced weaponry and space - time manipulation with the ninjas, leading to some really unique battles and alliances.
One idea could be a character who discovers a hidden power within themselves that changes their pre - determined path. For example, a character who was meant to be a simple peasant but then realizes they have magic that can make them a powerful leader. Another could be a time - travel plot where a character goes back in time to change an event that was supposed to lead to their downfall. Maybe a character was fated to die in a battle, but by changing a small decision in the past, they rewrite their entire future.
One idea could be to have the main character discover a hidden power within themselves that completely alters their destiny. For example, they might find out they can control time, and use this to prevent a great tragedy that was supposed to be part of their original fate.
A plot could revolve around Menchi's past. Maybe she has a hidden connection to a powerful group or a long - lost family member. This could lead to a story of self - discovery as she uncovers secrets from her past while still maintaining her role as a hunter and a food expert. She might have to face old enemies or make difficult choices regarding her new - found knowledge.
One idea could be the main character using gamer skills to quickly learn Nen abilities in unique ways. For example, they might have a leveling system for their Nen types, which gives them an edge in battles against other Hunters or enemies.