A possible plot could be that Naruto is sent back in time and meets Hashirama and Madara during their prime. He tries to prevent the feud between them from escalating. Naruto, with his modern - day knowledge and ideals, attempts to show them a different path for the ninja world. He might have to prove himself in battle against them first to earn their respect and then start to influence their decisions.
If Naruto meets Hashirama and Madara in fanfiction, Naruto could learn a great deal from Hashirama about building and uniting a village. Hashirama was the founder, after all. With Madara, Naruto might face some challenges as Madara had a very different view of the ninja world. However, Naruto's ability to befriend and understand his enemies could lead to an interesting turn of events. Maybe Naruto could even find a way to reconcile the two long - dead legends.
To develop Hashirama's ghost, we could give him a sense of purpose. He could be a protector of the village in the afterlife. So, when he senses a great danger approaching the village, he decides to reach out to Naruto. He could have a deep connection to the natural world even as a ghost, and his powers could be related to manipulating nature spirits. He could teach Naruto how to communicate with these spirits and gain their assistance in times of need.
In a fanfiction, Naruto could inherit some of the combined traits of Hashirama and Madara. For example, he might have Hashirama's ability to connect with nature on an even deeper level, while also having Madara's strategic mind. This would make him an even more formidable ninja. He could use these newfound abilities to face new and stronger enemies, like an ancient evil that once threatened Hashirama and Madara.
There's a fanfic called 'Hashirama's Guidance'. In this one, Hashirama comes back in a sort of spiritual form to guide Naruto. It delves deep into Naruto's growth as a leader, with Hashirama sharing his wisdom from his own experiences as the First Hokage. It's a very character - driven story.
Well, a big theme is legacy. Hashirama left a huge legacy for the village, and Naruto is constantly trying to live up to that while also making his own mark. There's also the theme of understanding different eras. Fanfics sometimes have Naruto learning about Hashirama's time, which was full of war and strife, and how that contrasts with his own relatively more peaceful (at least initially) era.
Well, Naruto is a main character in all Hashirama Naruto fanfics. He has his own personality, goals, and abilities that are further developed in these stories. Hashirama is also key. He is often portrayed as a mentor - like figure to Naruto. His influence on Naruto can be in terms of combat skills, understanding of the village's values, or even in Naruto's personal growth. Additionally, there could be other supporting main characters depending on the plot. For example, if the fanfic focuses on a war - time scenario, characters like Tobirama (Hashirama's brother) might also be main characters in that particular fanfic.
In some fanfictions, Naruto can be depicted as Hashirama's descendant. Fanfiction allows for creative interpretations, so authors might create a backstory where there is a family connection between them. However, in the original Naruto series, there is no such indication.
One great Hashirama Naruto fanfic is 'The Legacy of Hashirama'. It delves into how Hashirama's ideals influence Naruto in modern times. Another is 'Hashirama's Reincarnation', which has an interesting plot about Naruto being a reincarnation of Hashirama and the powers that come with it. And 'Hashirama and Naruto: The Bond' focuses on creating a unique bond between the two characters that wasn't explored much in the original series.
Fanfiction.net is also a good place to search. There are many Naruto fanfictions there. However, the search functionality might not be as refined as AO3. You may need to dig a bit deeper. Browse through the Naruto category and look for tags related to gay relationships between Naruto and Hashirama or just skim through the stories to find what you're looking for.