There could also be characters from the original series that interact with Harry in new ways due to his time - traveling and adopted status. For instance, Dumbledore might have a different relationship with Harry if he is adopted. He could be more of a mentor figure trying to guide Harry through the new changes in his life.
It's possible that the author might introduce some time - travel related characters, like time - guardians or beings that exist outside of normal time. These characters could either help or hinder Harry in his time - traveling adventures and understanding of his new adopted situation.
The main characters are Harry, who is used to being in the wizarding world of Hogwarts, and Selene. Selene is probably a powerful character with her own set of abilities. In the fanfic, their interactions will be the focus, as Harry adjusts to being adopted by her and they form a new kind of relationship.
Obviously, Harry Potter is one of the main characters. He is the one being adopted into the Greengrass family. Then, the Greengrass family members are important. There are likely to be the parents of the Greengrass family, and the Greengrass sisters. We might see Astoria Greengrass and her sister (if she has one in the fanfic). These characters will play significant roles in Harry's new life and the development of the story.
One interesting concept could be how Harry's actions in the past through time travel might change the future of the wizarding world in ways he didn't anticipate. For example, if he accidentally alters the relationship between certain families, it could have a ripple effect on the balance of power.
Scorpius Malfoy is another likely main character. His family's history and his own inquisitive nature would make him an interesting addition. He might be the one who discovers the time - travel mechanism. His relationship with Albus Potter could also be explored further as they embark on this time - traveling adventure together, and his views on his family's past actions could change during the journey.
Obviously, Harry Potter and Andromeda Tonks are the main characters. Harry is the well - known hero of the wizarding world, and Andromeda, as a member of the Black family who has broken away from their dark traditions, brings her own unique perspective and backstory to the time travel story.
Harry is the central character as the one being adopted. The Castle family members, such as the parents in the family, are main characters too. There could also be other family members like siblings or grandparents who interact a lot with Harry and shape his new life in this fanfiction world.
Harry is the central figure, but there might be a leader in Zeltech who plays a major role in the story. This leader could be a wise and powerful figure who sees something special in Harry. There could also be other young members of Zeltech who become Harry's friends or rivals as he adjusts to his new life.
In some fanfics, there could be a mermaid or a sea creature as a main character. The mermaid could have the power to help the boatbaby time travel, or they could be a key to solving some mystery in a different time period. For example, the mermaid might know the location of a magical item that the boatbaby needs to return to their own time.
Lily Luna Potter might also be a main character. She has a strong personality and her own set of skills. Her presence in the time - travel plot could bring a different perspective, especially when it comes to interacting with the female characters from the past.
Obviously, Naruto and Dante are the main characters. Naruto is the young ninja from the Hidden Leaf Village, known for his determination and his dream to become Hokage. Dante, on the other hand, is a powerful demon hunter from the Devil May Cry series, with his own set of unique skills and a flamboyant personality.