The neighbors could be in the story too. Quagmire, for instance. Peter might tell a story about how Quagmire got into a really embarrassing situation and how they all helped him out (or made it worse). Or he could include Cleveland and tell a story about a neighborhood barbecue gone wrong because of something Cleveland did.
Perhaps it's a story full of his own made - up characters. He might create a story about a superhero version of himself who saves the day in the most absurd ways. For example, he could use his love for beer as a superpower to defeat an evil villain who wants to ban all fatty foods in Quahog.
Obviously, there will be the princess herself. She is likely to be the central character, around whom the story unfolds.
Other Avengers might interact with Peter too. For example, Rhodey could befriend Peter and train with him. Or Natasha could teach Peter some spy skills, which could be useful for his superhero activities.
I think Rhodey would be a likely character. He was Tony's close friend, so he would be involved in verifying Peter's claim and guiding him. Also, Aunt May could play an important role. She has raised Peter and now has to come to terms with his new identity. And there could be some other Avengers like Natasha or Clint who knew Tony well and could offer their perspectives on this new family revelation.
I don't have information about this novel, so I can't tell who the main characters are apart from Jumper Griffin himself.
Obviously, Peter (presumably Peter Parker, Spider - Man) would be one of the main characters. And of course, the Avengers members like Iron Man, Captain America, Thor, Hulk, Black Widow, and Hawkeye are likely to be main characters too as they are the ones 'meeting' Peter.
The main characters are Peter and the Avengers. But we might also see some side characters like Happy Hogan who could be involved in some way. Maybe he's the one who arranges the initial meeting between Peter and the Avengers. And Pepper Potts could also make an appearance, giving her take on Peter's presence in the Avengers' world.
Well, obviously Peter Parker (Spider - Man) is one of the main characters since the story is about rescuing him. Then, of course, the Avengers. This would include Iron Man (Tony Stark), who would likely use his high - tech gadgets and suits to help in the rescue. Captain America (Steve Rogers) would bring his leadership and combat skills. Thor with his godly powers would also be a key figure, and Hulk (Bruce Banner) could provide brute force when needed.
Obviously, Tony and Peter are the main characters. Tony, with his genius intellect and wealth, and Peter, the young and spry superhero. There could also be other characters like Pepper Potts who might be involved in the story, perhaps trying to mediate between Tony and Peter or having an opinion on Tony replacing Peter.
Obviously, Harley would be one of the main characters as she is replacing Peter. And characters like Aunt May could still be in the story. She might be a bit confused at first about this new person in Peter's place.