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.
The Lords of the Netherworld were the First Master and Second Master, Judge Cui Jue, Judge Zhong Kui, Bull Head, Horse Face, Golden Shackle and Silver Lock, Black Impermanence, and White Impermanence.
Another great author could be Ryu. Ryu has a knack for creating unique plotlines that involve Hashirama and Naruto. They often incorporate elements from different arcs of the Naruto series in their fanfictions, which gives a sense of familiarity yet novelty. Their stories usually have great character development for both Hashirama and Naruto.
Madara Uchiha would be an excellent character to include. His long - standing relationship with Hashirama, filled with both friendship and enmity, and his connection to Sasuke and the overall ninja world's history would make for a very engaging fanfiction.
Tobirama should be included. As Hashirama's brother, he has a complex relationship with Hashirama. In a fanfic, his interactions with Naruto could be really interesting. Maybe Naruto could try to bridge the gap between Tobirama's old - fashioned views and the more modern ways of the village in Naruto's time.
Madara is quite commonly paired with Hashirama in crossover fanfiction. Their complex relationship in the original Naruto series makes for interesting scenarios when they are placed in different crossover settings. They could be forced to work together against a new threat or their rivalry could take on new dimensions in a different world.
Another popular pairing could be Hashirama with Mito Uzumaki. In fanfiction, this relationship can be explored in the context of how Hashirama's friendship with Madara might have affected his relationship with Mito. Also, how the power dynamics between the Senju and the Uzumaki clans were influenced by their union.
One possible antagonist could be those from other villages who see Naruto's new connection to Hashirama as a threat to their own power. They might fear that Naruto will use Hashirama's legacy to dominate in some way.
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.
The main antagonist could be a power - hungry shinobi within the same village as the descendant. This shinobi believes that they are more worthy of Hashirama's power and legacy. So, they scheme behind the scenes to undermine the descendant, spread false rumors about them, and even try to set up situations where the descendant would lose their life so that they can claim the power for themselves.