Another option is a crossover with the world of Harry Potter. The Final Fantasy 13 characters could attend Hogwarts. Lightning might be sorted into Gryffindor for her bravery, and then they all could get involved in the fight against Voldemort, using their unique abilities and magic from their own world.
A crossover with the Star Wars universe could also be exciting. Imagine the characters of Final Fantasy 13 in a galaxy far, far away. Snow could be like a Jedi, using his strong will and combat skills, while Fang might be more of a bounty hunter type, roaming the galaxy in search of valuable prey.
One idea could be a crossover with the 'Harry Potter' universe. Squall could be a wizard, and his gunblade could be enchanted. Another could be a crossover with 'Star Wars', where the characters from Final Fantasy 8 are in the middle of the galactic conflict. Maybe Laguna could be a Jedi - like figure.
One idea could be a crossover between Final Fantasy VII and Final Fantasy X. Imagine Cloud and Tidus teaming up to fight a new powerful enemy. Another could be a crossover with a non - Final Fantasy franchise like Pokemon. Picture Squall trying to catch Pokemon in the world of Final Fantasy VIII.
A 'Final Fantasy VIII Crossover Fanfiction' could involve crossing it with the world of 'Alice in Wonderland'. Rinoa could be like Alice, falling into a strange world where everything is topsy - turvy. The Heartless from Kingdom Hearts could also be added to the mix in a crossover. The characters of Final Fantasy VIII would have to fight these new enemies, with Squall taking on the role of a keyblade wielder in this strange new world.
One idea could be exploring the backstory of the main character's family in more detail. Maybe there were secrets or hidden powers within the family that were never fully explored in the game.
One idea could be a crossover with another popular RPG like Dragon Quest. The characters from World of Final Fantasy could end up in the world of Dragon Quest, facing new enemies and having to adapt to different magic systems. For example, the mirages in World of Final Fantasy might interact in strange ways with the slimes in Dragon Quest.
One idea could be to have Harry Potter characters enter the world of Final Fantasy VII. For example, Harry could end up in Midgar and meet Cloud. They could team up to fight against the dark forces in both their worlds, like Voldemort's minions and Sephiroth. The magic from the Harry Potter universe could interact in interesting ways with the materia and summons of Final Fantasy VII.
How about a crossover with 'Final Fantasy'? The different job classes in Final Fantasy could be compared to the various character types in Warhammer Fantasy. For instance, the Black Mages in Final Fantasy could team up with the Warhammer Fantasy mages to cast powerful spells against a great evil. And the idea of having Warhammer Fantasy's Chaos forces corrupt some of the beautiful and idyllic worlds in Final Fantasy could create a really dark and engaging story.
Maybe the Philosopher's Stone in Harry Potter has some connection to a powerful crystal in Final Fantasy. Voldemort wants to use it to gain ultimate power, and the heroes from both universes have to come together to protect it. For example, Cloud Strife could join forces with Harry and his friends. The Hogwarts houses could be compared to the different classes in Final Fantasy, like Gryffindor being similar to the Warriors in Final Fantasy.
Well, a really cool plot could be that the Mass Effect Relay network somehow gets connected to the Crystal Materia in Final Fantasy. This causes chaos as both universes start to blend. Characters from both sides have to figure out how to separate the two worlds again. Along the way, they discover that there are ancient forces at work in both universes that are related. Tali could use her engineering skills to help repair some of the damaged Crystal Materia, while Squall could teach her some sword - fighting techniques from his Gunblade.
One idea could be a crossover with 'Rick and Morty'. Gary could team up with Rick and they'd have some wild adventures across different dimensions. Maybe they'd encounter some new alien species together that are a combination of the creatures from both shows.