Here's a plot idea. There is a Transformer that has the ability to use the Force. It was created by an ancient civilization that combined their knowledge of the Force and technology. This Transformer travels through the Star Wars galaxy, trying to find others like it. Along the way, it gets involved in various battles and political intrigues, and it has to decide whether to use its powers for good or be swayed by the dark side.
A cool plot idea could be that the Transformers are mistaken for a new type of Sith - created abomination. The Jedi initially try to destroy them, but then realize they are something different. Another idea is that a Transformer becomes a Jedi Knight, using its unique abilities in combat and its own code of honor which is similar to the Jedi Code.
One idea could be a crossover where the characters from Transformers Prime end up in the Beast Wars universe. They could form alliances with the Beast Wars characters to fight a common enemy like the Predacons. Another idea is to explore the origin stories of some of the Beast Wars characters within the context of the Transformers Prime lore. Maybe there's a hidden connection between a Prime character and a Beast Wars character that could be uncovered.
Perhaps Vergil is from a parallel dimension where the Devil May Cry world and the Transformers Beast Wars world are already intertwined. He comes to the Beast Wars universe to seek a powerful artifact that could help him in his own dimension's battles. Along the way, he forms unexpected alliances with both Autobots and Maximals, and his presence changes the course of the Beast Wars as the different factions either see him as a threat or an opportunity.
One plot idea could be that the Star Trek crew discovers a planet where Transformers have been in a long - standing war. The Enterprise crew tries to broker peace between the Autobots and Decepticons. Another could be a situation where the technology of the Transformers somehow gets integrated into the Star Trek universe's ships, creating super - powered vessels. Or perhaps a Transformer gets beamed onto the Enterprise and has to adapt to life among the crew while they figure out how to send it back to its own world.
A great plot for Star Wars The Clone Wars fanfiction could be centered around a new, unknown planet that gets caught in the middle of the war. The planet has its own unique species and culture. The story could follow how the clone troopers and the Jedi interact with this new civilization, whether they try to protect it or use it for their own strategic advantages. Or perhaps a story where a group of clone troopers start to develop their own individual personalities and question their loyalty to the Republic due to some unethical orders they receive. This could lead to a conflict within the clone ranks and force the Jedi to take sides.
One idea could be exploring the origin of a new, mysterious force - user in the Shadow Wars. Maybe it's a forgotten Jedi or Sith technique that resurfaces and causes chaos. Another could be focusing on the relationship between a group of rebels and how they deal with the added threat of the Shadow Wars.
One idea could be exploring a hidden planet during the Dark Voyage. The Maximals and Predacons could discover a new energy source there that changes the power dynamics. Maybe there are ancient Transformers on this planet with unique abilities.
A third storyline could be about a lost Transformer that crash - lands on a Star Wars planet. The local inhabitants, be it the Ewoks or some other species, help the Transformer repair itself. In the process, they learn from each other's cultures and technologies, and the Transformer eventually becomes a protector of the planet against other threats in the galaxy.
One plot idea could be that Godzilla somehow gets transported to the Star Wars universe. Maybe the Empire tries to capture and weaponize it, leading to a big showdown between the rebels and the Empire over Godzilla.
A great plot for Star Wars Kamino fanfiction could involve a lost Jedi Padawan who ends up on Kamino. The Padawan discovers that the Kaminoans are experimenting with a new type of clone that has Force - sensitive abilities. This discovery puts the Padawan in a difficult position as they have to decide whether to report it to the Jedi Council or try to stop the experiments on their own. Another idea is to write about a clone who starts to have memories of a previous life and realizes that he was cloned from a person with a very different moral code. He then tries to break free from the programming of the Kaminoans and find his own identity. Also, a story about a smuggler who lands on Kamino and gets caught up in the politics between the Kaminoans and the Galactic Republic could be really interesting.
One idea could be a mercenary who is hired by a mysterious Sith Lord to steal a powerful Jedi artifact. The mercenary then has to navigate through various planets, dealing with both Jedi and Sith along the way.