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 possible plot could be that in a post - apocalyptic future, Gohan and Trunks team up to fight against a new and powerful enemy that has emerged. They train together, with Gohan sharing his knowledge of the old martial arts techniques and Trunks bringing in his own combat skills developed from years of fighting alone. Their bond grows stronger as they face challenges, and eventually they manage to defeat the enemy, saving what's left of the world.
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.
Definitely their strong bond. They have been through so much together, so highlighting their loyalty and trust for each other is great. Also, their different fighting styles can add action - packed scenes. For example, Gohan's more methodical and strategic approach against Trunks' more impulsive and aggressive style.
One common theme is friendship. Since they are two of the last remaining warriors in a desolate future, their friendship is crucial. They support each other, whether it's in battle or in dealing with the emotional toll of their situation.
One idea could be a crossover with the Dragon Ball Super universe. Future Gohan could meet the present - day Goku and Vegeta. They could train together and learn new techniques from each other. Another plot could involve a crossover with the Naruto universe. Gohan might use his ki powers in the ninja world, and perhaps have to face off against powerful ninja like Naruto or Sasuke. He could also learn some ninja skills in return.
The contrast between their characters. Gohan is more of a gentle and studious type, while Future Trunks is a tough warrior from a post - apocalyptic future. Their interactions can create really interesting dynamics in fanfiction. It's like seeing two different worlds collide.
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 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 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.