Zeus could be one. He is a powerful god in Greek mythology and might be interested in Harry's story. Another could be Odin from Norse mythology, known for his wisdom. And perhaps Isis from Egyptian mythology, as she has powers related to magic and protection.
One of the main gods could be Apollo. He is associated with light and prophecy in Greek mythology. His knowledge of prophecy could be crucial for Harry. Then there's Thor from Norse mythology. His strength and courage could inspire Harry. Also, Anubis from Egyptian mythology might be involved. His role in the afterlife and judgment could bring a new dimension to the story as Harry might have to deal with the concept of life and death in a different way.
It could be Zeus. He is a powerful god and might see Harry as a worthy candidate for training. He could teach Harry about leadership and power control.
Well, it could be that the gods see Harry's plight at the Dursleys and decide to take him in. Maybe they give him new powers, train him in godly magic that's different from what he learns at Hogwarts. He could also be sent on quests related to both the wizarding world and the realm of the gods.
It could be the Sage of Six Paths. Since he is a very powerful and almost god - like figure in the Naruto universe. He might have decided to take Naruto under his wing to further his growth.
It could be the Greek gods. For example, Athena might bless him with wisdom, which would help him in his studies at Hogwarts and in outsmarting his enemies. Zeus could give him the power of lightning, a very powerful offensive ability.
The Chaos Gods themselves could be the main antagonists. Their very nature is to create chaos and disorder, which would be directly opposed to the order and stability that Hogwarts and the wizarding world try to maintain.
The four gods in this fanfiction could be created to fit the unique world of Harry Potter. They might be named after something related to the wizarding world, like one could be the God of Magic Wands, another the God of Potions, etc. However, this is just speculation. It really depends on the creativity of the fanfiction writer. They could also be based on the four elements, with each god having control over one element, like fire, water, earth, and air, and these elements play a crucial role in the magic of the Harry Potter universe as described in the fanfiction.
It's hard to say for sure without reading it, but it could be that Harry, Hermione, and Ron still play major roles. They might be interacting with the gods in some way, either seeking their help or being caught in the middle of a conflict involving the gods.
Zeus is a possibility. As the king of the gods, he might see Percy's potential and adopt him to have an ally among the demigods. Another could be Poseidon, since Percy is already his son in the original story. It would be an interesting twist to have Poseidon formally adopt Percy in a more divine way.
The main character is Harry Potter without a doubt. However, there could be a whole host of other characters. We might see Dumbledore or other Hogwarts professors making an appearance, trying to understand or guide Harry in this new situation. And then there are the god - characters. They could range from powerful and benevolent deities who want Harry to succeed in his new role as champion, to more malevolent ones who see him as a threat or a tool for their own ends. There could also be new characters created specifically for this fanfiction, like other champions from different magical communities who are also vying for the title or recognition from the gods.
Obviously, Harry Potter would be the main character. He would be the one with the new role as the master of the Nordic gods. Hermione and Ron could also be involved. Hermione would be very interested in learning about the Nordic magic and gods, and Ron might be there to provide some comic relief and also be a loyal friend in the new adventures.