Well, they could also change their own relationships. Maybe Naruto wouldn't be so alone as a child, and Ino could become a stronger ninja earlier. They might train together in ways they didn't before, using the knowledge of future jutsu and strategies. They could also influence the relationships between different ninja clans, like improving the relations between the Uzumaki and the Yamanaka clans.
It could be the same antagonists as in the original Naruto series at first, like the Akatsuki. But if Naruto and Ino change things, new antagonists might emerge. Maybe some ninja who were once allies turn against them because they fear the changes Naruto and Ino are making to the ninja world order.
In a time - travel fanfiction like this, they could also have the opportunity to meet long - lost characters or discover secrets that were lost in time. Naruto and Shikamaru could learn about the origin of some of the powerful jutsus in their world. And perhaps they could use their knowledge of future technology or ninja tools to create something revolutionary in the past. This could potentially change the balance of power among the ninja villages. However, they would also have to be careful not to be discovered as time - travelers, as that could lead to all sorts of complications.
Well, they could change a lot of things. Maybe Naruto would prevent some of the tragedies that happened in the past. He could stop the Nine - Tails attack on the village, which would completely change his own life and the lives of many in Konoha.
If Naruto and Hinata went back in time in fanfiction, one possibility is that they could change the course of many events. For example, Naruto might be able to prevent some of the tragedies that occurred in his childhood. Hinata could also use her knowledge to help her clan earlier. They might also have the chance to influence the relationships between different characters in a positive way, like improving the relations between the Uchiha and the village.
Well, one possibility is that they could completely rewrite the history of the ninja clans. Naruto, with his positive influence, might be able to make the Uchiha clan feel more accepted in the Leaf Village, preventing the Uchiha massacre. Obito, having seen the destruction his actions caused in the future, could help Naruto in these efforts. Also, they could work together to train younger versions of themselves and their friends to be even stronger, which would have a huge impact on future battles.
Well, they might change some important events. For example, they could prevent certain tragedies from happening in the wizarding world. Maybe they'd save some characters who died in the original timeline.
They might change some crucial events in their past. For example, Stefan could prevent some of the bad things he did while being a ripper. Caroline, on the other hand, could go back to when she was a human and make different choices about her relationships or her path in life.
Well, they might prevent some great tragedies in the Star Wars universe. For example, they could stop Anakin from turning to the Dark Side. This would completely change the course of history in the galaxy.
In fanfiction, if Goku and Vegeta go back in time, they might change the course of history. For example, they could prevent some of the villains from ever becoming powerful. They may also meet their past selves, which could lead to some really interesting battles or training sessions. And they could introduce new techniques to their past counterparts, making the Saiyans even stronger earlier in the timeline.
Maybe they would meet their ancestors. Percy could see his Greek hero predecessors and Artemis might interact with the first hunters she ever had. This could lead to some interesting exchanges, like learning forgotten hunting techniques or ancient combat skills.