Besides Naruto, it could be that the main characters include some of the gods from God of War 4. For example, Odin. He could be intrigued by Naruto's powers and try to either use him or destroy him. And Naruto would have to use his wits and strength to deal with this powerful and conniving god, making for a great power struggle in the fanfiction.
Naruto and Atreus could be the main characters. Naruto, with his exuberant and positive personality, could contrast well with Atreus' more somber and in - process - of - growing - up nature. They could learn from each other and face challenges together, like dealing with the various mythical creatures in the God of War 4 world.
Orochimaru might also be a main antagonist. He is always after power and knowledge. In the context of the 4th war with a god involved, he could see the god as a source of ultimate power. So he might try to manipulate the situation to either steal the god's power or use Naruto to get to the god's power. He could be secretly working behind the scenes, causing trouble for Naruto and his allies.
It could be the traditional God of War villains like the gods who oppose Izuku. Maybe Ares, if he's still around in the fanfiction's version of the God of War world, would see Izuku as a threat and try to stop him.
There could be an ancient evil force that awakens because of Luffy's new powers. This force was once sealed away but now wants to destroy Luffy and everything he stands for, seeing him as a disruption to the balance it once knew.
Obviously, the god and goddess of war are main characters. They would likely have their own distinct personalities, powers, and backstories.
Sakura could be one of the main female characters. She has always had a connection with Naruto, and after the war, her feelings might have changed or deepened. Hinata is also a likely candidate as she has long - admired Naruto. And perhaps some new characters from other villages could be introduced as well.
Kratos is surely one of the main characters. He is the central figure in the God of War series.
In the 'God of War 3 Novel', the central character is Kratos. He is the driving force of the story, seeking revenge on the gods. Zeus is a major character as he is the main target of Kratos' wrath. Also, Athena has an important part as she has a complex relationship with Kratos. Other gods such as Hermes also make appearances and are part of the conflicts that Kratos faces.
The main characters in God of War 4 story are Kratos and his son Atreus.
Since I don't know the exact 'the god of war novel', it's hard to say. But surely the god of war himself would be a main character. There might also be other gods or goddesses who interact with him, like his allies or enemies.
The main character is Kratos. He is a Spartan warrior seeking revenge. Another important character is Ares, the God of War, who plays a major role in Kratos' story.