The main character is Naruto as the whole concept of the golden chakra cloak revolves around him. Hinata could also be involved as she has feelings for Naruto. In some fanfictions, the Akatsuki members might be the antagonists trying to take the power of the golden chakra cloak from Naruto. They could see it as a threat to their plans. There could also be some old and powerful ninja from Naruto's village who either help or oppose Naruto's new power depending on their own beliefs and motives.
Naruto is, of course, the central figure. Sakura might be involved as she is part of Naruto's team. Additionally, characters like Jiraiya could make an appearance in the fanfiction. Since Jiraiya was Naruto's teacher, he could have some knowledge about the golden chakra cloak that he imparts to Naruto either in flashbacks or in spirit form. And there could be new characters created specifically for the fanfiction who are either allies or enemies because of the golden chakra cloak.
Obviously Naruto is the main character as the golden chakra cloak is related to him. Sasuke might also be involved as his rival. Kakashi could play a role as Naruto's mentor, guiding him in controlling this new power.
In many naruto golden chakra fanfiction, Naruto is at the center. Kakashi could be an important character as he is Naruto's mentor. He might guide Naruto in controlling and using the Golden Chakra. Hinata could also be a main character, as she has deep feelings for Naruto. Her love for Naruto could be a driving force in some stories, either giving Naruto emotional support as he deals with the power of the Golden Chakra or even having her own role in helping him unlock more of its potential.
In Naruto dark chakra fanfiction, Sasuke is frequently a central figure. Given his complex character arc and his inclination towards power - seeking, it's easy to envision him being affected by or exploring dark chakra. Naruto too can be a main character. His strong will and connection to positive chakra could be put to the test when faced with the allure of dark chakra. Another character often involved is Kabuto. He has a history of being involved in dark and underhanded schemes, so it's not a stretch to see him in stories centered around dark chakra. There are also some original characters created by fanfiction authors that are specifically designed to interact with the concept of dark chakra in unique ways.
Sakura is often involved. Since she's a medical ninja, it's natural for her to be associated with the chakra scalpel in fanfiction. She might be seen using it in new and innovative ways to save lives or in battles against strong opponents. Another common character is Naruto himself. Even though he's not primarily a medical ninja, in some fanfics, he could learn to use the chakra scalpel in his own unique way, perhaps combining it with his massive chakra reserves and shadow clone jutsu.
Naruto himself is often involved. Since he is the main character of the original series, it's natural for him to be part of fanfictions related to the chakra fruit. He might be the one to discover it or have to protect it from villains.
Sasuke could be another key character. There could be a plot where Sasuke is initially skeptical about Naruto's new chakra sage abilities but then comes to see their value in protecting the shinobi world. And Jiraiya, as Naruto's former mentor, might appear in flashbacks or even in some spiritual form to give Naruto advice on his chakra sage journey.
Sasuke can also be involved. Maybe he's initially skeptical of Naruto's connection with the Golden Wolf and this causes some tension between them. Later, they might have to work together to deal with the implications of the Golden Wolf's presence.
Well, in some fanfictions, the golden chakra cloak could lead to Naruto having unique abilities. For example, he may be able to teleport short distances or have enhanced sensory perception. It could also be a plotline where Naruto has to learn to control this new form without it overwhelming him. There might be a story where the other villages see Naruto's new power and become either afraid or try to steal the secret of the golden chakra cloak.
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. 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.
Sasuke can also be a central figure. His quest for power in the original Naruto makes him a prime candidate in fanfictions about godlike chakra. He might either gain it on his own or be in a rivalry with Naruto over it, leading to intense battles and power struggles.