A great concept is the crossover of the Sith Lords from KOTOR with the Sith in the main Star Wars story. This could create intense power struggles and ideological battles. For instance, a KOTOR Sith Lord might challenge Darth Vader in a battle of wits and the Dark Side powers, which would be really exciting to read as it would show different interpretations of the Sith code and how they apply their powers.
In some Star Wars KOTOR crossover fanfiction, there are concepts of alternate timelines. Maybe a character from KOTOR ends up in a different era of the Star Wars timeline, like during the Clone Wars. This can lead to all sorts of interesting interactions, such as the character having to adapt to the different political situations and technologies of that time while still using their KOTOR - trained skills.
One interesting concept could be the interaction between the Federation in Star Trek and the Galactic Republic in Star Wars. For example, how would their different forms of government and ideologies clash or cooperate? Another concept might be the use of technology. Star Trek has the transporter and Star Wars has the hyperdrive. How would characters from each universe react to the other's technology? Also, the idea of Jedi and Vulcans interacting due to their shared emphasis on mental discipline is really cool.
In Naruto Star Wars crossover fanfiction, an exciting concept is the idea of jutsu being used in place of some Star Wars technology. For instance, teleportation jutsu instead of hyperdrive for faster travel. Also, the idea of different Naruto clans being like different species in the Star Wars universe. The Uchiha could be like a powerful, secretive group similar to the Sith, but with their own code of honor based on their Naruto background.
One interesting concept could be the power levels. In DBZ, characters have extremely high power levels through ki. In Star Wars, the Force is a different kind of power. A crossover could explore how these two power systems interact. For example, a Saiyan using the Force or a Jedi using ki techniques.
One interesting concept could be a character from Star Wars, like Luke Skywalker, finding himself in the world of Aladdin. He might use the Force in ways that seem like magic to the people of Agrabah. For example, he could levitate objects, which would be similar to Aladdin's magic carpet. Another concept could be Darth Vader arriving in Agrabah and causing chaos. His dark presence would be a huge contrast to the usually colorful and lively world. It could lead to a great story of good vs. evil where Aladdin and his friends have to use their wits and unique abilities to combat Vader.
Well, a cool idea in Twilight - Star Wars crossover fanfiction could be a love story between a Twilight character, like Bella, and a Star Wars character, perhaps a dashing X - Wing pilot. The cultural differences between the two universes would add a lot of drama. Also, the Volturi (from Twilight) could be seen as a sort of Sith - like organization in the Star Wars galaxy, with their thirst for power and control over the vampire world.
One interesting concept could be the combination of the Servant system from Fate and the Force in Star Wars. For example, a Jedi could be summoned as a Servant, bringing their unique lightsaber skills and connection to the Force into the Fate universe's battles. Another concept might be how the different classes in Fate, like Saber or Archer, would interact with the various species and factions in Star Wars.
One interesting concept could be Buffy characters having to adapt to the use of the Force in the Star Wars universe. For example, Buffy herself might struggle to understand the different rules of combat when faced with lightsabers and Force powers. Another concept could be the Jedi or Sith being introduced to the concept of slaying vampires and demons like in Buffy's world.
Well, a great concept might be the appearance of Star Wars' iconic spaceships in the Disney universe. Imagine the Millennium Falcon flying over the landscapes of a Disney - like fantasy world. It would be a sight to behold. And also, the characters from both universes could embark on adventures together, like Han Solo and Mickey Mouse teaming up to save both their worlds from a common threat.
One interesting concept could be the meeting of different species from both universes. For example, seeing how a Wookiee from Star Wars would interact with a Vulcan from Star Trek: Voyager. Another might be the exchange of technology. The lightsabers of Star Wars and the phasers or replicator technology from Star Trek could lead to some really cool scenarios. Also, the moral and ethical differences between the two franchises could create some intense storylines when the characters collide.
One interesting concept could be the introduction of characters from other universes into the Galactic Empire's power structure. For example, a character with unique magical abilities might disrupt the Empire's order. It could also be about how the technology of the Galactic Empire interacts with different fictional technologies in the crossover.