One common theme is the clash of different worlds. Since it's a crossover, you often see the unique settings of each original work collide. For example, if it's a Durarara!! and Bungo Stray Dogs crossover, the normal yet chaotic Ikebukuro and the world full of gifted individuals with special abilities from Bungo Stray Dogs create a lot of interesting situations.
Character development is also a big theme. Writers like to take characters from different series and put them in new situations to see how they grow. In a Durarara!! and Naruto crossover, for instance, the Naruto characters might learn about the more modern and complex society of Ikebukuro, while the Durarara!! characters could be influenced by the ninja values of Naruto. This mutual influence leads to new aspects of their personalities emerging.
The theme of identity is often explored in durarara crossover fanfiction. For instance, when crossed with 'Psycho - Pass', the question of what defines a person in a society with strict moral evaluation (Psycho - Pass) and in the chaotic, diverse world of Durarara becomes a central point. Another common theme is the struggle for power. When combined with 'Attack on Titan', the fight for survival and power in both universes makes for a very engaging narrative.
One common theme is the OC trying to fit into the chaotic world of Durarara. They often have to deal with the various gangs and strange characters. Another theme is the OC having some sort of special power or knowledge that changes the dynamics of the Durarara world. And sometimes, there's a theme of friendship or romance between the OC and the existing Durarara characters.
One common theme is the mystery around Izaya. Female characters are often intrigued by his complex and somewhat devious nature. They might try to figure him out, which leads to interesting interactions.
One common theme is the clash of cultures. For example, when the Mandalorian crosses with a different sci - fi universe, like Star Trek. Their warrior culture and strict code often contrast with the more diplomatic or utopian ideals of the other universe.
One common theme is the clash of different moral codes. For example, when Daredevil crosses over with characters like Punisher, their views on justice can be very different. Another theme is teamwork. Characters from different backgrounds have to learn to work together.
One common theme is the clash of different powers. For instance, when Ninjago characters cross over with characters from other universes like Power Rangers, their unique fighting styles and powers collide. It creates exciting battle scenes where they have to figure out how to work together despite their differences.
One common theme is adventure. Since Technoblade is known for his Minecraft adventures, many crossovers put him in new and exciting places to explore. Another theme is friendship. For example, when he crosses over to other Minecraft communities, he often forms new friendships or rivalries with the characters there.
One common theme is the clash of different power systems. For example, when Berserk crosses with a series like 'Naruto', the magic and brute strength in Berserk contrast with the chakra - based powers in Naruto. Another theme is the exploration of different moral compasses. Characters from Berserk, which has a rather dark view of the world, interact with characters from more idealistic series, leading to interesting moral debates.
Power struggles are common. When Lucifer crosses over with other universes or characters, there's often a battle for dominance, like in crossovers with other powerful supernatural beings. Each character tries to assert their power and influence.
One common theme is culture shock. When characters from different worlds come to Earth, they experience new cultures, languages, and social norms. Another theme is power dynamics. If powerful characters from another realm arrive on Earth, it changes the balance of power. Also, the theme of adaptation is often present as the characters have to adapt to Earth's environment.