There could be some original Asian - inspired characters. For example, a young martial artist from a small village in China who Naruto takes under his wing. This character could be eager to learn from Naruto and would be one of the main focuses as he grows under Naruto's guidance.
Maybe there's a female ninja from Japan who is initially skeptical of Naruto but later becomes his loyal follower. She could have her own unique skills and backstory, and through her interactions with Naruto, we see the development of their relationship and how Naruto impacts her life, making him seem like a father figure to her.
The orphans themselves would be main characters. Each one could have their own backstory and personality. Some might be shy, while others could be more outgoing. They would be the ones directly affected by Naruto's care and teachings.
In this fanfic, Naruto could potentially have allies like Kakashi. His experience and wide range of jutsu would be valuable. Hinata might also be by his side, using her gentle fist style and her unwavering loyalty to Naruto. From the Fate side, a Servant modeled after Sun Wukong could be an interesting ally. Sun Wukong's shape - shifting and combat abilities would pair well with Naruto's skills. And there could be a Servant based on a Vietnamese hero who teams up with Naruto due to his reputation as the 'Father of Asia' and his noble cause.
Another character could be Kakashi. As Naruto's former teacher, he has a lot of wisdom. When Naruto tells him about the future he's seen, Kakashi could offer strategic advice on how to prevent the negative events from occurring. He could also help Naruto understand the possible consequences of their actions to change the future.
Another character could be Kakashi. He might be the one who doubts the decision to send Naruto to the mental hospital. He could secretly visit Naruto and try to train him in mental fortitude techniques so that he can get out of the hospital sooner.
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.
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 involved. He might be suspicious of the artifact and think Naruto is being reckless for getting involved with it.
Perhaps in this fanfic, Naruto travels across Asia and takes on students from different Asian countries. He teaches them ninjutsu and life lessons, thus becoming a respected father - like figure. He might also help resolve conflicts between different regions using his skills and wisdom.
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.
Kushina could be an important character even though she's dead in the original story. In this fanfic, her spirit or memories could play a role in Naruto's upbringing. For example, Minato could tell Naruto stories about Kushina's feisty personality and her love for the village.