Another theme is the exchange of knowledge. For instance, a character from the past might have some unique skills or knowledge that is valuable in the future, and vice versa. They then share and learn from each other, like an ancient herbalist teaching future doctors about natural remedies that have been forgotten.
One way is through time - travel jutsu. A character could accidentally or intentionally use a jutsu that sends them to the future or past. For example, Naruto might find a hidden scroll with a time - travel jutsu and end up in the future where he sees how his friends and the village have changed. This could lead to interesting storylines where he tries to fix things or learn from the future.
One idea could be a time - traveling hero from the past who gets stuck in a high - tech future world and has to adapt to new technologies while using his old - fashioned skills to solve problems. For example, a medieval knight in a world of flying cars and laser guns.
One possible plot could be that future Gohan travels back in time to warn the past about an upcoming threat that was not properly dealt with in his own timeline. He might meet the past version of himself and try to train him to be stronger, sharing his knowledge of the future battles. Maybe he also meets the past versions of his friends and family, and has to convince them of the seriousness of the situation without revealing too much about the dark future he comes from.
One common theme is redemption. Characters from the past might have made mistakes and in the future - set story, they get a chance to make up for it. For example, a character who was once a villain in the past might find a way to redeem themselves in the future. Another theme is the cycle of life. The past and future are often used to show how things come full circle, like how a character's actions in the past lead to consequences in the future that in turn affect the past again. And of course, the power of memory. How memories from the past shape the future and how characters deal with forgotten or recovered memories is also a big part of these fanfictions.
One common theme is self - discovery. When Naruto from the past goes to the future, he often has to re - evaluate who he is in the context of this new world. Another theme is the impact of the past on the future. It shows how the actions and decisions made in the past can have far - reaching consequences.
Past Percy is likely to be more impulsive. He hasn't faced as many challenges yet and might act before thinking. Future Percy, on the other hand, would be more cautious and calculating, having learned from past experiences.
A plot where the past and future ninja teams have to compete in a tournament. Each team has their own set of skills and strategies based on their time periods. The past teams might rely more on brute force and basic jutsu, while the future teams have more advanced and unique jutsu. It would be a great opportunity to see the evolution of ninja techniques and how the different generations interact.
Toothless is another great candidate. As Hiccup's dragon, he has a unique bond with his rider. In a past - meets - future story, he could be the one to sense the disruptions in time. He might also meet his descendants or ancestors in the future or past dragons, which could lead to some really interesting interactions. For example, an ancient dragon from the past might teach Toothless a long - lost skill that helps them in a future battle.
One possibility is that future Naruto could give past Naruto some advice on how to handle his relationships better. For example, with Sasuke. He might tell him to be more understanding and patient. Also, future Naruto could show past Naruto some of his new jutsu and inspire him to train harder to reach that level.