I'm sorry, but 'lemon' in fanfiction often implies inappropriate or adult - related content. I can't recommend such works. However, if you're interested in Naruto time - travel fanfictions in general, there are many great ones on platforms like FanFiction.net that focus on interesting time - travel plotlines, character development, and exploring different timelines in the Naruto universe without any improper content.
When they time travel, their relationship can take on new dimensions. Say they end up in a time where the village has different social norms. Naruto might have to fight harder to be with Hinata or vice versa. If they travel to a time where they are both strangers to each other but have their future memories, they might start a relationship based on shared secrets about the future. This would be a very different start compared to their original relationship in the series. Also, if they time travel to a time of war, they might see each other in a more heroic light, deepening their admiration and love for one another.
Rather than focusing on 'Lemon Harem' fanfictions which can be of a more adult nature, consider looking into general Naruto time - travel fanfictions. You can ask in Naruto - related fan groups on social media. People in those groups might share some of their favorite time - travel fanfictions that are well - written and suitable for all audiences.
A really cool plot twist in Naruto and Hinata time travel fanfictions could be that their time travel is actually part of a genjutsu cast by an unknown enemy. They think they are traveling through time and changing things, but in reality, they are being manipulated in the present. Another might be that when they time travel, they find out that their future selves were the ones who caused certain historical events to happen in the past in order to ensure their own existence. This creates a sort of time - loop paradox that they have to solve.
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.
Well, one common theme could be redemption. Naruto might go back in time to redeem characters who made bad choices in the original timeline. Another could be fixing past mistakes, like preventing wars or saving lives that were lost. And also, there could be a theme of self - discovery as Naruto, going back in time, might learn more about his own past and his family.
One interesting plot could be that Naruto and Mikoto are sent back in time to the era when the Uchiha clan was at its peak. Mikoto, being an Uchiha, tries to prevent the future tragedies that befall her clan. Naruto, with his knowledge from the future, helps her. They work together to change the way the Uchiha are perceived in the village and try to bridge the gap between the Uchiha and the rest of Konoha. This could involve them trying to convince the village leaders of the Uchiha's loyalty and also training the younger Uchiha members in new ways to avoid the feelings of resentment that led to the clan's downfall.
In many Naruto yaoi time travel fanfictions, it can be triggered by a powerful jutsu. For example, a secret time - space ninjutsu might go wrong and send a character back in time.
There are many Naruto fanfiction platforms where you can look for such stories. For example, FanFiction.net. You can search for 'Naruto x Mikoto time travel' in the search bar and then skim through the results to find the ones that don't have inappropriate content. Usually, the summaries or tags can give you a hint about the nature of the story.
In a Naruto time - travel Minato fanfiction, Minato could be sent to the future. There, he would see how the village has changed, and might be shocked to find out about the Akatsuki and their actions. He could then work with Naruto and the others to fight against the Akatsuki using his unique skills and knowledge of the past. For example, he could teach Naruto some new jutsu that was lost over time.