Adaptation is also a key theme. Nnoitra has to adapt to new environments, whether it's a different time period, a new world with different physics, or a society with different social hierarchies. This can lead to some really interesting character development as he tries to find his place in these new situations.
One common theme is the 'opposites attract' concept. Since Nnoitra has a rather rough and aggressive personality, the contrast with the reader's more normal or gentle nature is often explored. Another theme is the idea of redemption. Nnoitra may be seen as a character who can be redeemed through his relationship with the reader.
Well, 'Nnoitra Meets the Mysterious Realm' is another interesting one. This fanfiction has Nnoitra crossing into a realm filled with mysterious creatures and powers. He has to use his strength and wits to survive and figure out a way back home. The detailed descriptions of the new realm and Nnoitra's reactions make it a captivating read.
A common theme is the struggle for acceptance. The minotaur, being a different and often feared creature, usually has to fight to be accepted in the new world or by the new group of characters it crosses over with.
One common theme is power struggles. Since there are different powerful characters from various planes, they often clash over control or resources. For example, in many fanfictions, two powerful planeswalkers might fight for dominance over a newly discovered plane.
Power is a common theme. Since Vegeta is extremely powerful, seeing how his power compares to characters from other universes is always interesting. Another theme is culture clash. For instance, when Vegeta enters the Harry Potter world, his Saiyan warrior culture clashes with the wizarding culture. Pride is also a theme. Vegeta's Saiyan pride often plays a role in how he interacts with characters from other fandoms.
Survival is also a big theme. Characters in the crossover fanfiction usually have to figure out how to survive in the presence of Annabelle, especially if they come from a world where they're not used to such malevolent supernatural forces.
One common theme is the idea of redemption. Raphael, who has a somewhat dark past in the original lore, often goes through a journey of redemption in these crossovers, especially with Simon's influence. Another theme is friendship. Despite their differences, they form a strong bond.
Another theme is power exploration. Naruto and Sakura have their own set of powers from the Naruto universe. When they are in a crossover, they often have to figure out how their powers work in relation to the new world they are in. This can lead to some really interesting battles and power - up moments as they learn to adapt and use their skills in new ways.
The theme of redemption also shows up sometimes. Despite being a fearsome character, in some crossovers, Deathwing might be given a chance to redeem himself. Maybe he caused a lot of destruction in his original world, but in the crossover world, he has the opportunity to do good deeds and change his reputation.
One common theme is power exploration. Writers often explore how Tsuna's powers interact with the powers in the crossover universe. For example, in a crossover with a superhero universe, how Tsuna's unique abilities compare to superpowers like flight or super strength.