Jason Grace could be a main character as well. His leadership skills and his connection to the Roman side of the mythology would add an interesting dynamic to the story, especially when traveling back in time and interacting with different versions of the gods and heroes.
Definitely Percy Jackson. He's one of the central characters in the 'Heroes of Olympus' series, so it's very likely he would be involved in a time - traveling adventure.
Annabeth Chase would also be a main character. Her intelligence and strategic thinking would be crucial when dealing with the challenges of a different time period. Plus, she and Percy often work together in these stories.
Well, it could be about the heroes going back to prevent a great disaster that originally happened in the past. For example, they might try to stop the rise of a powerful enemy before it got out of control.
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.
Filch could be a key character too. Harry going back in time might mean more opportunities to outwit Filch and his attempts to catch students misbehaving. This would add a lot of comical moments as Filch is always so serious about his job and Harry could use his time - traveling knowledge to drive Filch crazy with his pranks.
Obviously, Percy Jackson could be a main character. He has a lot of experience and his powers would be useful in different time periods. Annabeth Chase too, with her intelligence she could figure out how to deal with the challenges of different eras. Jason Grace might also be a main character as his leadership skills could come in handy during time - travel adventures.
Leo Valdez is another character who could be a star. His ability to create and manipulate fire can add a lot of excitement to party games. He could be involved in a game where he has to use his fire to light up targets or keep a magical fire - based object alive for a certain amount of time.
Naruto is a must - have main character. He's the one who would likely drive the story forward with his determination and unique abilities. Then there could be characters like Hercules from the Olympus side. He and Naruto could have an interesting dynamic, maybe starting as opponents and then becoming friends. And Sakura could also be a main character, representing the medical ninja skills in this strange crossover world.
Jason Grace is one of the main characters. He has leadership skills and is a son of Jupiter. He plays a crucial role in many of the group's adventures.
Annabeth Chase would also be a main character. Her intelligence and strategic skills would be important in the rebuilding efforts. And of course, her relationship with Percy is a major aspect of the story.
Some of the main characters are Percy Jackson, Annabeth Chase, Jason Grace, Piper McLean, etc.
Obviously, the Marauders themselves, which include James Potter, Sirius Black, Remus Lupin and Peter Pettigrew.