Obviously, the Weasleys themselves would be the main characters. There's Molly and Arthur, the parents. And of course, their kids like Fred, George, Ron, Ginny and the others.
In this fanfiction, it's highly likely that the main characters would be the Weasley family members. Arthur Weasley would be really interested in Muggle artifacts. He might drag the whole family into his exploration of the Muggle world. Ron, being Harry Potter's best friend, could act as a sort of bridge between the wizarding world and the Muggle world for his family. Ginny, with her feisty nature, might have some interesting interactions with Muggles too.
The Weasley family is bound to be the central focus in 'Weasleys Meet the Muggle World Fanfiction'. Molly Weasley would be concerned about how her family behaves in the Muggle world. She might be constantly warning them not to do anything too outlandish. Fred and George would bring their mischievous ways into the Muggle world, creating all sorts of chaos and laughter. And the younger Weasleys would be learning about the strange Muggle customs and trying to adapt, while still maintaining their unique wizarding identities.
Well, perhaps the Weasleys would be completely bewildered by Muggle technology like the television. They might accidentally turn it on and be startled by the moving pictures.
Obviously, Hermione and the Weasleys. Hermione is the one doing the saving, so she is the central character. The Weasleys as a whole family would also be important, including characters like Molly, Arthur, Ron, Ginny and the others.
Well, Harry Potter is the central figure, but the Weasley siblings are key too. Fred and George could be like his fun - loving older brothers, teaching him all kinds of mischievous spells and pranks. Ginny would be like a sister, and their relationship could develop in a really interesting way. And Percy, despite his differences from the rest of the family, would also be an important character as Harry would be part of the family dynamic that Percy is also a part of.
Obviously, the four main Turtles - Leonardo, Donatello, Raphael, and Michelangelo are going to be main characters. They are the core of any TMNT story. They'll probably be the ones interacting with the other versions of themselves in this 'Meet the Turtles' concept.
The marauders are the central figures from the past. James Potter could be a fun - loving grandfather, Sirius Black the cool and rebellious one. Remus Lupin would be the wise and kind grandfather. Their grandchildren could be a diverse bunch. There might be a Potter grandchild who is a bit of a troublemaker like James was. A Black grandchild who is very proud of their family heritage. And perhaps a Lupin descendant who is very studious and wants to learn all about Remus's life. Peter's grandchild might be a character who is trying to find their place in the family after Peter's betrayal.
Obviously, the Avengers members like Iron Man, Captain America, etc. And the Warrior 3 which include Fandral, Hogun and Volstagg.
The main characters could be the political leaders of the nations and the confederacy. They would be the ones making the big decisions in diplomatic meetings and negotiations. For example, a president or a prime minister from a nation, and a council leader from the confederacy.
Obviously, Percy is one of the main characters. And then there would be various gods like Zeus, Poseidon, Athena, etc. These gods play important roles in Percy's world and their interactions with him would be central to the story.
Splinter is also likely to be a main character. He is the turtles' master and mentor, and his wisdom often guides them in difficult situations. In this fanfiction, he might play a crucial role in helping the turtles face new challenges.
Obviously, Rhodey and the Avengers members like Iron Man, Captain America, Thor, Hulk, etc. would be the main characters.