The main characters in 'children of the future fanfic' could be children from different social backgrounds. For instance, there might be a poor orphan who discovers he has the ability to control time, and a rich kid who uses his family's advanced technology to help the group. There could also be a young scientist - in - training who is trying to figure out the secrets of the future world and is leading the other children in their adventures.
Aside from Harry's children, their friends at Hogwarts could also be main characters. For instance, a new character who comes from a different wizarding family but has a special connection with Harry's kids. Maybe they team up to solve a mystery in the school, like a hidden chamber or a strange magical phenomenon.
Since I don't have specific details about this 'reading the future fanfic', it's hard to say who the main characters are. It could be the ones who have the power to read the future, or it might be the people around them who are affected by this ability.
Since I haven't read the fanfic, I can't say for sure. It could be original characters created by the fanfic author, or it might feature characters from an existing franchise that the fanfic is based on.
Most likely, Marty McFly would still be one of the main characters. He's the central figure in the original movies and would probably play a major role in the fanfic set in 2015. Doc Brown would also be there, as he's the inventor of the time - travel technology and Marty's mentor. There could also be Biff Tannen or his descendants, as they often cause trouble in the 'Back to the Future' universe.
There's no way to know precisely without reading the 'watching the future fanfic'. But generally, there could be a group of friends or comrades who are facing the challenges of the future together. One of them could be a leader - type character with strong leadership skills. There might also be antagonists, perhaps those who want to control the future for their own selfish gains or those who oppose the positive changes that the main characters are trying to bring about.
Often, the main characters are the titular 'children of the dark'. They could be young individuals with unique abilities related to the dark, like being able to see in complete darkness or having a connection to shadow creatures. For example, there might be a character named Alex who is a natural leader among them.
In addition to the Potter children, their friends at Hogwarts could also be main characters. They might play important roles in the adventures the Potter kids go on, like helping them solve mysteries or fight against villains.
Since I don't know the specific 'children of science fanfic', it's hard to say. But it could be the children themselves who are the main characters, with different personalities and skills related to science.
Maybe a group of friends who form a gaming team. Each friend has a different specialty in the game, like one is great at combat, another at strategy, and one at finding hidden treasures. They work together to achieve victory in the game world.
One option for the main character could be the child of Jake Sully and Neytiri. This character would inherit the unique skills and knowledge of their parents and face new challenges in the ever - evolving world of Pandora.