In RWBY and Final Fantasy fanfiction, a great crossover idea is the character interaction. Characters from RWBY like Weiss, who has a more aristocratic background, could interact with Final Fantasy characters from noble families. They could exchange knowledge about their respective worlds' social structures, magic, and combat techniques. This would lead to some really interesting story developments as they learn from each other and face common enemies together.
One interesting crossover could be the combination of RWBY's unique combat styles with Final Fantasy's magic systems. For example, Ruby's scythe - wielding skills might be enhanced with some of Final Fantasy's fire or ice magic spells. It would create really dynamic and visually stunning fight scenes.
A cool crossover might involve the jutsu in Naruto being combined with the spells in Final Fantasy 14. Picture Sasuke using a spell like Blizzard III from Final Fantasy 14, but with his own Uchiha - style twist. Also, the ninja villages in Naruto could be compared to the city - states in Final Fantasy 14. The fanfiction could explore how the politics and power dynamics of both worlds interact when characters from each are forced to cooperate. Maybe the Hidden Leaf Village and Limsa Lominsa form an alliance to fight a common enemy that threatens both their existences.
One interesting crossover could be the characters from Naruto using the Materia from Final Fantasy 7. For example, Naruto with the Fire Materia could enhance his Rasengan with fire elemental powers. It would be a really cool visual to see.
A crossover could involve the ninjas from Naruto's world being intrigued by the magic in Final Fantasy 7. Gaara's sand powers could be compared to some of the earth - based magic in FF7. For example, his sand might interact in interesting ways with spells like Quake. In a fanfiction, they could all participate in a tournament where ninjas and FF7 characters show off their skills, and Naruto and Gaara have to adapt their fighting to the different rules of the FF7 universe.
One interesting crossover could be the use of magic systems. In Harry Potter, magic is more about spells and incantations, while in Final Fantasy 12 there are various magicks like black, white, and green magick. A fanfiction could explore a character from Harry Potter learning the magick system of Final Fantasy 12, perhaps Hermione trying to study the more scientific approach to magic in Final Fantasy 12.
One interesting crossover could be characters from Final Fantasy having to navigate the political intrigue of Westeros. For example, Cloud from Final Fantasy VII might find himself in King's Landing. His combat skills could be put to use in the battles for the Iron Throne. He'd probably be a bit confused by all the backstabbing and political games, as he's used to more straightforward battles against Sephiroth and the Shinra.
A great aspect of a Final Fantasy 10 and Kingdom Hearts fanfiction crossover could be the character relationships. Yuna and Sora, for instance, could form an interesting friendship. Yuna's calm and spiritual nature might contrast and complement Sora's more impulsive and adventurous side. They could learn from each other's experiences, with Yuna teaching Sora about the summoning and the fayth, while Sora shows Yuna the power of the Keyblade and the importance of believing in oneself in the face of great evil.
A crossover might involve the storylines. Picture the ninja world of Naruto facing a threat similar to the fal'Cie in Final Fantasy XIII. The shinobi could team up with the characters from FF XIII to fight this common enemy. The different cultures and power systems would create a really engaging and unique story.
In some Naruto x Final Fantasy fanfiction, the summons in Naruto could be related to Final Fantasy summons. Like the toads in Naruto could have a connection to a similar creature from Final Fantasy. This would create unique interactions between the two universes.
Some cool crossovers might include Naruto's summoning jutsu being used in the world of Final Fantasy X - 2. He could summon giant toads or snakes, which would be a strange sight in Spira. The Al Bhed language from Final Fantasy X - 2 could be something Naruto characters have to learn. And perhaps the Farplane in Final Fantasy X - 2 could have a connection to the afterlife in the Naruto universe. This could lead to some really deep and emotional storylines where characters from both worlds interact with the concept of death and the afterlife.
One interesting crossover could be the use of magic spells from Harry Potter in the world of Final Fantasy 7. For example, a character might use 'Expelliarmus' to disarm a Shinra soldier. Another could be the appearance of Final Fantasy 7 creatures in Hogwarts. Imagine a Chocobo running around the Quidditch pitch! Or perhaps a character from Final Fantasy 7 attending Hogwarts and having to learn about magic while also using their own unique abilities.