Well, one possibility is that Naruto with the Rinnegan could use his newfound power to protect Kushina during their time travel. Maybe he can prevent some of the tragedies that happened in the past. For example, he could stop the Nine - Tails attack on the village by controlling the beast in a more efficient way with his Rinnegan powers.
Another thing that could occur is that they might run into some powerful enemies from the past that they have to face together. Naruto's Rinnegan would give them an edge, but it would still be a tough battle. They could end up changing the course of history in ways they didn't expect, like influencing the relationships between different clans or even changing the way ninjas are trained in the past.
One possibility is that Naruto with his Rinnegan powers could disrupt the power balance in the Sannin era. His modern jutsu and knowledge might give him an edge. For example, he could use his Rasengan in ways that the shinobi of that time have never seen. He might also form unexpected alliances, like befriending Orochimaru before he goes bad, which could change the entire future of the Naruto world.
One possible plot could be that Naruto somehow inherits the Rinnegan from an unexpected source and Kushina, being his mother, helps him understand and control this new power. Maybe they discover a hidden connection between the Uzumaki clan and the Rinnegan's origin, leading them on a journey to uncover secrets long lost in the ninja world.
The story could start with Naruto suddenly finding himself in the past with Kushina. He'd be shocked at first but then realize the potential of his Rinnegan in this new situation. He might start by using it to gather information about the past and any threats that could harm Kushina or the village in the future.
Well, when it comes to Naruto time travel and Rinnegan in fanfics, it's often about exploring new storylines. Maybe Naruto himself gets the Rinnegan and travels back in time to train his younger self. This would make him a much more powerful ninja at an earlier stage and could completely change the power balance in the Hidden Leaf Village and among the other ninja villages as well.
A possible plot could be that Naruto and Kushina are sent back in time due to a powerful jutsu gone wrong. Once in the past, they decide to prevent the Nine - Tails attack on Konoha. Kushina, with her knowledge of sealing techniques and Naruto's combat skills, could work together to stop the masked man who released the Nine - Tails. This would save many lives and change the future for the better.
Well, in this fanfiction scenario, perhaps Naruto's Rinnegan gives him unique abilities during the time travel. He and Anko could team up to take on threats that were previously unbeatable. They might also discover secrets about the origin of the Rinnegan or other powerful jutsus that were lost in time. It could be a story of self - discovery for both of them as they navigate a different era.
Well, Naruto might break a bond with Kushina in the fanfiction. Maybe he finds out some dark secret about her that makes him question their relationship.
There could be a scenario where Kushina comes back to life somehow in the fanfiction. She might then play matchmaker between Naruto and Hinata, using her knowledge of Naruto to help Hinata understand him better. For example, she could share stories of Naruto's childhood that would make Hinata feel closer to him.
In this fanfiction, their marriage could also lead to new ninja techniques being developed. Kushina was a powerful kunoichi, and Naruto has his own unique abilities. Combining their skills and knowledge, they could create something entirely new. This could have a significant impact on the Hidden Leaf Village, making it even stronger in the face of threats.
Well, Naruto with the Rinnegan trained by Jiraiya would be extremely powerful. Jiraiya could teach Naruto unique ways to use the Rinnegan's abilities. Maybe Naruto would combine Sage Mode with the Rinnegan powers, creating new and unbeatable jutsu. He could also use the Rinnegan's ability to see chakra flow to better understand his opponents and counter their attacks more effectively.