Neville Longbottom is a wonderful character to add. He has grown so much throughout the series and can be a great support to the trio. Dumbledore, even if in a ghost - like or memory form, can offer his great wisdom. Also, Draco Malfoy can be included in an interesting way. Maybe in fanfiction, he has a change of heart and teams up with the trio against a greater evil.
The Weasley family members are always good to include. Ron's siblings can bring in different elements. For example, Fred and George with their pranks and inventions can add some humor. Ginny, being Harry's love interest, can be a strong female character in the fanfiction. And Professor McGonagall, with her strict but fair nature, can be there to guide the trio when they are in trouble.
Fred and George Weasley could be really fun to include. Their prank - loving nature and inventiveness could add some humor and unexpected solutions to the problems the Golden Trio might face in fanfiction. Additionally, Remus Lupin would be a great fit. His knowledge of dark creatures and his kind heart could make him a valuable ally for the trio.
The characters in the 'dark trio' in the fanfiction are likely to be those who have a propensity for the dark arts or have some sort of malicious intent. It could be that the author takes minor characters from the original series and gives them more prominent roles within this dark context. For example, Crabbe and Goyle could be developed further into more menacing characters, or perhaps some of the Death Eaters that were not as well - explored in the original books could be part of this trio.
Hermione is always a great character to include. As a kid, she could be shown solving even more complex problems than in the books. Her intelligence and determination can drive the plot forward in fanfiction.
Obviously, Harry and Gabrielle themselves are essential. But characters like Hermione can add a lot too. She could be the one to help Gabrielle with her studies when she visits Hogwarts. Ron can also be there for some comic relief and to show the difference between the Hogwarts and Beauxbatons students.
Definitely Dumbledore. His wisdom would be crucial in guiding Harry and Maxima in any situation. Hermione would also be great as she could research and figure out how Maxima's powers work in relation to magic. And of course, Hagrid, who could introduce Maxima to the more unique and dangerous magical creatures in the wizarding world.
Luna Lovegood would be an interesting character to include. Her unique perspective on magic could help Harry and Molly in unexpected ways. For example, she might know of some strange magical creatures that are relevant to a mystery they are trying to solve. Hagrid is another great choice. His love for magical creatures and his big heart could bring a lot to the story. He could help Molly and Harry take care of some new and dangerous magical beasts that show up in the fanfiction.
Obviously, Harry, James, and Lily should be central. But Sirius Black would be a great addition. He was James' best friend, so he could provide a lot of insights into their friendship and the time they spent together at Hogwarts. Also, Remus Lupin could be included as he was part of their group. He could add depth to the story by sharing his memories of James and Lily.
Well, obviously Goku, Vegeta, and Gohan are the core Super Trio. But you could also include Piccolo. He has a long history with Gohan and his strategic mind could add a lot to the team. Another great addition could be Trunks. His future - knowledge and sword - fighting skills can bring a new dynamic.
Dumbledore would be an interesting addition. He has a lot of knowledge and power, and his interaction with Merlin would be fascinating. Ron could also be included for some comic relief and his loyalty would be an asset in any adventure that combines the two universes.
Well, Sirius Black could be an interesting character to put in a 'Harry Potter Dursleys fanfic'. Since he was Harry's godfather, his presence could stir things up for the Dursleys. He might be furious at how they treated Harry and take some sort of action. Hermione and Ron could also be included. They could visit Harry at the Dursleys' and be shocked at the living conditions. Their reactions and how they interact with the Dursleys could make for an exciting plot. And of course, the Weasley family as a whole. Their warm and loving nature would contrast greatly with the cold Dursleys.