Well, in this 'naruto son of samul fanfic', it's likely that Naruto's friends remain important characters. Sasuke could be intrigued by Naruto's new heritage and might even be a bit jealous. Sakura could be concerned about how this new identity affects Naruto's place in the village and in their team. Then there could be some new characters who are related to Samul's past. Maybe an old rival of Samul who now has an issue with Naruto because of his relation to Samul.
Samul, of course, since he's Naruto's supposed father in this fanfic. He could be a powerful ninja who had some great influence in the past. Another character could be Naruto's mother, who might have a different story now considering her relationship with Samul. Also, characters like Jiraiya could still play an important role. He might be the one to guide Naruto in understanding his new identity as Samul's son and help him train to face the challenges that come with it.
One main character could be an old friend or ally of Samul. This person could hold the key to many secrets about Samul and Naruto's family. They could help Naruto understand his father better. Also, the Hokage at that time, whether it's the Third Hokage or someone else, would still be an important character. They would have to deal with Naruto's new status as the son of Samul, which could have political implications in the village. And of course, any potential enemies of Samul who might now target Naruto would be significant characters in the fanfic.
Well, it could be about Naruto having a different origin as the son of Samul. Maybe it explores how this new identity affects his relationships in Konoha. For example, his friends like Sasuke and Sakura might react differently to him. Also, it could change the way the village elders view him, perhaps with more suspicion or higher expectations.
There could be Sasuke. Since Naruto's situation changes, Sasuke might play a different role in this fanfic, either as an ally or a rival in a new way. Another might be Kakashi. He could be the one guiding Naruto through his discovery of being the son of chaos.
Sasuke could be one of the main characters. He might be suspicious of Naruto's new powers and how they change Naruto. Their relationship could become more complex as Sasuke tries to understand if Naruto is still the same person he knew.
Sasuke could be one of the main characters. He might be initially skeptical or even hostile towards Naruto's mermaid side, but as the story unfolds, he could come to understand and support Naruto. Another character could be Sakura. She could use her medical ninjutsu skills to help Naruto if he gets injured during his underwater adventures.
Another main character could be Kakashi. As Naruto's mentor, he would have to guide Naruto in understanding and using his powers related to being Raizen's son. He might also be the one to protect Naruto from those who would seek to harm him because of his new identity.
Well, in addition to Naruto, Gaia herself could be considered a main character in a sense, even if she might not be a physical presence all the time. If the fanfiction delves into Naruto's heritage, there could be other characters related to Gaia's past or other 'sons' or 'daughters' of Gaia in the Naruto world. And of course, Naruto's friends like Sakura would also be important. Her reaction to Naruto's new identity could range from shock to being supportive, and she might be involved in Naruto's new adventures related to his connection to Gaia.
Hinata is also a likely main character. In the original story, Hinata has a crush on Naruto. With Naruto being a smooth operator, he might notice Hinata's feelings more easily and their relationship could develop in a more romantic and interesting way. Kakashi could also be involved. Naruto could use his smoothness to learn new jutsu from Kakashi more effectively or to get Kakashi to trust him with more important missions.
The street kids themselves would be main characters. They could be a diverse group with different personalities and backstories. There might also be Naruto's friends like Sakura and Kakashi who could play important roles. Sakura could help with the kids' medical needs, and Kakashi could offer his wisdom in training the kids.
Sakura could be a main character. She might be the one who takes on a motherly role towards baby Naruto. She'd be very protective and try to teach him basic things. Kakashi could also be important. He'd use his wisdom to figure out how to deal with this situation and also keep an eye on Naruto's safety.
Sakura could be a main character. Since it's Naruto returning to Konoha, Sakura, being his friend and a strong ninja in her own right, might play a big role. Maybe she's the one who first welcomes Naruto back and they team up to face any threats.