It's also possible that civilians who get caught up in the war in a significant way could be main characters. For example, a scientist who discovers something that could change the balance of the war, or a journalist who is trying to expose the truth about the war to the world. These types of characters can bring a different perspective to the story compared to the military - focused characters.
Well, it could be about a world war where all the participating sides have equal strength in terms of military might, technology, and resources. Maybe it shows how the balance of power creates a complex and intense war situation, with no one side having an easy advantage at the start.
Since it's a fanfic, the main characters could be original creations of the author. They might be leaders trying to navigate their countries through this unexpected and late - coming world war. Or perhaps they are ordinary people who find themselves in extraordinary situations because of the war. Maybe there are also some resistance fighters or spies that play crucial roles in the story.
Tris and Four would likely still be main characters. Their relationship has been a central part of the Divergent series, and in a post - war scenario, they would be key in leading the rebuilding efforts or in bringing about change.
Sasuke could also be a main character. His power and his complex relationship with Naruto would play a role. He might have his own reasons for wanting to either defeat or control the Beast of War, perhaps related to his quest for power or revenge. And Sakura, with her medical ninjutsu skills and her growth as a fighter, could be crucial in treating the wounded during the battles against the beast. She might also have some unique insights into the nature of the beast based on her studies.
The golden trio, no doubt. Harry, who has to find his place in a world that has changed so much after the war. Ron, who might be exploring new career opportunities in the wizarding world. Hermione, who could be using her knowledge to bring about positive changes. And don't forget their families. The Weasleys, especially, would be an important part of their post - war lives as they are like a second family to Harry.
Percy Jackson himself is almost certain to be a main character. After all, the fanfiction is centered around him after the war. Annabeth Chase would also likely be a main character, as she is Percy's love interest and a powerful demigod in her own right. Grover, Percy's best friend, would probably be there too, still looking out for nature and helping Percy in his new adventures.
The Straw Hat Pirates would probably be the main characters. Luffy, with his determination and leadership, would be right in the middle of the action. Zoro, with his powerful swordsmanship, would be crucial in battles. Nami could use her knowledge of the weather to gain an advantage. And other members like Sanji, Usopp, and Chopper would also play important roles.
The two of them could also interact with the Ministry of Magic officials. Harry, being a hero of the war, would have a certain influence. He might try to push for reforms in the Ministry, and Daphne could support him. They would have to deal with bureaucrats who may not be as eager for change, like some of the old - guard pure - bloods who still hold positions of power in the Ministry.
I think Nico di Angelo could also be a central character. He has his own unique powers and backstory, and after the giant war, he might be involved in some of the darker or more mysterious aspects of the post - war world, like dealing with any remnants of the Underworld's connection to the giants' plans.
Obviously Naruto would be the main character since it's about him time - traveling. Sasuke would also likely play an important role. Maybe he's skeptical of Naruto's time - traveling claims at first but then comes to believe him and helps him change things. Kakashi could also be a major character, providing guidance to Naruto based on his own experiences.