Kakashi could be another popular character. His experience and wisdom might be used in fanfiction to either study the Satsui no Hado or to try and prevent its spread. He has a deep understanding of different powers in the Naruto world, and so his inclusion in stories related to this power can add an interesting layer of depth.
In this type of fanfiction, there could be a concept of the Satsui no Hado being combined with other powers or elements in the Naruto world. Like, perhaps it could be merged with a nature transformation, such as lightning or fire, creating a whole new and extremely powerful ability. This would not only change the power dynamics in battles but also open up new storylines for the characters involved.
It could be a rogue ninja from a forgotten clan who has mastered the Satsui no Hadou and wants to use it to take over the ninja world. This character might have a vendetta against the major ninja villages and see Naruto as a major obstacle.
One possible fanfiction could be about Naruto learning a new jutsu similar to Hado 90 from another dimension. Maybe he meets a strange ninja who teaches him this powerful technique. Naruto then has to master it quickly to defend his village from a new threat.
Naruto is often very popular. His outgoing personality and determination make him a natural fit for the rockstar world. Fans love to imagine him on stage, rocking out and inspiring the crowd.
Kakuzu is another character that can be popular in these fanfictions. His unique ability to have multiple hearts and his money - loving nature can add a touch of humor or be explored in more serious ways in relation to the Akatsuki's goals and activities.
Naruto himself is often a popular character in such fanfictions. His popularity in the original series makes him a natural focus for new and cybernetic - themed storylines. Sasuke is also quite popular as fans like to explore how his Sharingan could be enhanced with cybernetic elements.
Naruto himself is often a central and very popular character in these fanfictions. Since it's about his rebirth, readers are interested in seeing how his character evolves differently.
In Naruto fanfiction, Sasuke is often very popular. His cool and brooding nature makes for interesting storylines. Naruto himself is also a common focus. In Megaman fanfiction, Megaman and Proto Man are popular. Their heroic personas and their relationship as brothers or comrades are often explored in different ways.
Twilight Sparkle from My Little Pony is also quite popular in these crossovers. Her intelligence and powerful magic make her a great counterpart to Naruto. She can have really interesting interactions with Naruto, whether it's about sharing knowledge or working together in battles.
In 'alchemist naruto fanfiction', Naruto is surely one of the most popular characters. He could be the one to bridge the gap between the ninja world and the world of alchemy. Sakura is also a likely popular character. Her intelligence and medical skills could be developed further in a story with alchemical elements, like using alchemical knowledge to improve her medical ninjutsu. Another popular character could be Itachi. His complex backstory and powerful abilities could be intertwined with alchemist concepts in really interesting ways.