One idea could be a crossover with the Dragon Ball Super universe where Future Trunks teams up with Goku Black from an alternate timeline. They could be forced to work together against a new, powerful enemy that threatens both their timelines. Another plot could involve a crossover with the Naruto universe. Future Trunks could end up in the Hidden Leaf Village and learn about chakra. He might then combine his ki powers with some ninja techniques to fight a common foe. A third idea is a crossover with the One Piece world. Future Trunks could land on the Grand Line and join forces with the Straw Hat Pirates. They would have to face off against the Marines and other pirates while also trying to find a way for Trunks to get back to his own world.
Well, for a Future Trunks crossover fanfic, you could have him cross over with the DC universe. Imagine Future Trunks meeting Superman. They could have an epic battle at first due to misunderstandings, but then realize they have a common goal of protecting their respective universes from a great threat like Darkseid. Or perhaps a crossover with the Star Wars universe. Future Trunks could be on a planet in the Star Wars galaxy and get involved in the conflict between the Jedi and the Sith. He could use his swordsmanship skills and ki blasts in lightsaber - like battles. Also, a crossover with the Harry Potter world. Future Trunks could end up at Hogwarts and use his powers to help the students fight against Voldemort and his Death Eaters.
A possible plot for a Future Trunks crossover fanfic is a crossover with the Gundam universe. Future Trunks, with his combat skills and technology from his world, could collaborate with Gundam pilots. They could face off against a new type of mobile suit created by an evil organization that wants to conquer both the Dragon Ball and Gundam universes. Another option is a crossover with the Pokemon world. Future Trunks could land in the Pokemon world and start catching and training Pokemon. He might use his ki to enhance the strength of his Pokemon in battles against Team Rocket or other villains. And a crossover with the Mortal Kombat universe. Future Trunks could be drawn into the Mortal Kombat tournament and use his martial arts skills along with his ki powers to fight against the likes of Shao Kahn and his minions.
A crossover with the Star Wars universe would be cool. Future Trunks could find himself on a planet in the Star Wars galaxy. Maybe he has to help the Jedi fight against the Sith. His superhuman strength and ki blasts would be a new and powerful element in the Star Wars battles. He could learn about the Force while also teaching the Jedi about ki energy.
One idea could be a crossover with 'Doctor Who'. The DeLorean could time - travel to a universe where the Doctor exists, and they team up to fix a time rift that's threatening both their timelines. Maybe Marty and the Doctor have to figure out how to combine the technology of the TARDIS and the DeLorean to set things right.
In a fanfic like this, the cultural clash would be interesting. Future Trunks comes from a world of high - tech and space travel, while the Fire Emblem world has its own medieval - like setting with magic and knights. He could introduce new ways of fighting and thinking to the Fire Emblem characters. For example, his knowledge of energy blasts might inspire some mages to try and develop similar attacks using magic. And the Fire Emblem characters could teach him about the use of magic and the importance of strategy in battles, which is different from his more straightforward combat style in his own world.
One idea could be that Goten and Trunks accidentally travel to an alternate dimension where their roles are reversed. Goten could be the more studious and reserved one while Trunks is the carefree fighter. They have to figure out how to get back while also dealing with the differences in this new world.
Perhaps a plot where Future Gohan and Future Trunks accidentally travel to an alternate timeline. There, they have to team up with different versions of themselves to defeat a common enemy. This would involve exploring how they interact with these alternate selves and how they adapt to the new environment and challenges.
One idea could be that Trunks discovers a new power while on a mission, and Bulma helps him control it in a unique way. Maybe she creates a device that can enhance his power but also has some unforeseen side effects that lead to some comical and heartwarming moments between them.
One idea could be Future Trunks bringing back a technology from the future that changes the course of the present timeline's battles. For example, a more advanced scouter that can detect hidden power levels more accurately.
One idea could be that in a post - apocalyptic future where Trunks is the last hope, Broly somehow appears. Maybe Broly has lost his memory and Trunks tries to train him to use his power for good. Another plot could be a time - travel accident that brings Broly to Trunks' time. They initially fight but then realize they need to team up against a common enemy like a new form of the Androids.
A good crossover idea is that the Akatsuki from Naruto are interested in the technology that Future Trunks has. They might try to steal it for their own purposes. This could lead to a series of battles and alliances. Also, since both Future Trunks and Naruto have a strong sense of justice, they could start a movement in both worlds to promote peace and cooperation between different races and species.
One idea could be that Broly and Trunks are forced to team up against a new, powerful enemy that threatens the entire universe. They start off not getting along because of Broly's wild nature and Trunks' more calculated approach. But as they face challenges together, they gradually learn to respect each other's strengths and form a deep bond.