One idea could be a time - travel scenario where Naruto is sent back in time and meets Hashirama. He could learn about the founding of the village directly from Hashirama and they could team up to face some early threats to Konoha that were previously unknown. Another could be a story where Hashirama's spirit somehow inhabits Naruto's body for a short time, and Naruto has to deal with having Hashirama's power and knowledge while also trying to keep it a secret from his friends.
An ancient evil force that was sealed away by Hashirama long ago could be released in Naruto's time. This entity, having a grudge against Hashirama for imprisoning it, would see Naruto as an obstacle too since he's allied with Hashirama. It could have powers that are completely unknown to the modern ninja world.
Hashirama's revival might also bring back old wisdom and knowledge. He could teach the new generation of shinobi things that have been lost over time. However, there could also be political issues. Some might not be happy with a long - dead Hokage coming back and potentially interfering in current affairs. And his revival could also have an impact on Naruto's own growth. With Hashirama around, Naruto might have to re - evaluate his role as a leader and a shinobi.
In some fanfictions, Naruto might use a powerful jutsu. Maybe he discovers an ancient sealing technique that can bring back the dead for a short time. He could also have found some rare chakra-infused artifact that has the power to revive the First Hokage.
Tobirama, Hashirama's brother, can also be a popular character in these fanfictions. His views on Madara and his relationship with Hashirama can add an extra layer of drama to the story.
One interesting plot could be their early days of friendship and how it gradually evolved into a complex relationship filled with respect and rivalry. They could be shown training together and sharing their dreams for the future of the ninja world.
One idea could be Naruto traveling back in time and meeting Hashirama. They could team up to face a new, powerful enemy that threatens the very foundation of the ninja world. Naruto's modern techniques combined with Hashirama's wood - style jutsu would make for some epic battles.
I really like the idea of a fanfic called 'Flowers and Fire'. In this story, fem Madara and fem Hashirama start off as enemies but gradually discover they have more in common than they thought. Their relationship could be explored in a way that shows how two powerful female ninjas can change the shinobi world together. It would have some great action scenes as well as tender moments between them.
It could be an ancient evil spirit that was sealed away by Fem Hashirama in the past. Now that she has resurfaced in the Naruto - era, the spirit is also awakened. This spirit wants to destroy the world that Fem Hashirama once protected and Naruto, being the hero of his time, stands in its way along with Fem Hashirama.
Their relationship can be developed through shared dreams. In the fanfiction, they could start having the same strange dreams that show them memories from their past lives together. This would make them start to question their connection and lead to them spending more time together to figure it out.