Sometimes, characters from other villages might also be involved. Maybe a ninja from Konoha who has a special encounter with the Nidaime Otokage. This could lead to an interesting exchange of ideas or a conflict that drives the story forward.
One possible interesting plotline could be the exploration of the Nidaime Otokage's relationships with other Hidden Villages. Maybe he had secret alliances or rivalries that are not fully explored in the original Naruto series.
Often, Naruto himself might be associated as he is the main character of the original series. Writers may give him the devil bloodline to explore how it changes his character and abilities.
Naruto himself could be one. Imagine him getting a hold of a legendary weapon that enhances his already powerful Rasengan. Sasuke is also a likely candidate as his quest for power could be intertwined with a legendary weapon.
Naruto himself is often associated with it. Since he is the main character of the series, many fanfictions explore his potential with the Lightning Armor. He might learn to use it in unique ways, like combining it with his Rasengan.
Naruto himself could be one of the main characters associated with it. Since he has such iconic spiky hair, it's easy to imagine him developing some unique hair jutsu. Sakura might also be involved, as her long hair could be used in interesting ways in fanfiction. And Sasuke, his cool and somewhat long hair could also be a factor in hair jutsu - related stories.
Sasuke might also be a main character in such fanfiction. His Sharingan and his own strong chakra could potentially be used in relation to the chakra arrow. He could use his Sharingan to predict the path of the chakra arrow or enhance its power.
Sasuke is often a character associated with black chakra in fanfiction. Given his natural inclination towards power and his dark past, it's easy to imagine him being connected to such a powerful and mysterious form of chakra.
Often, Naruto himself might be associated with it. Writers could explore the idea of Naruto unlocking the Celestial Release as a new power, perhaps during a time of great need in the story. This would give him an edge against powerful foes.
Often, Naruto himself might be associated with it. Since he has a large amount of chakra and is always looking for new ways to fight, the chakra bow could be something he discovers or is given. Another character could be Sasuke. His Sharingan might give him a unique advantage in using the chakra bow, like being able to accurately aim at distant targets.
Often, Naruto himself might be associated with it in some fanfictions. Given his status as the protagonist, it's not uncommon to give him such a powerful ability. Another could be Sasuke, as his power - hungry nature in the original series could be explored further with the God Release.