There could be a rival con artist group. They might see fem Harry as competition and try to sabotage her operations or even eliminate her. They could be more ruthless and experienced, making them a formidable foe for her.
The Ministry of Magic could be a major antagonist. Since fem Harry is a con artist, they would see her as a threat to their order and secrecy. They might send Aurors after her to stop her schemes.
The Death Eaters could still be the main antagonists. They might see Fem Harry Potter's new - found goddess - like powers as a threat to their plans of taking over the wizarding world. So they would try to stop her at all costs.
It's also possible that in this fanfiction, the Titan world has its own set of political or power - hungry groups who oppose Fem Harry. These could be organizations or factions that don't like the changes she's bringing or the influence she's starting to have in their world.
The traditional wizarding authorities could be antagonists. Since Fem Harry Potter is into pirate stuff which might be seen as unorthodox in the wizarding world, they could try to stop her from following this new path.
Obviously, Fem Harry Potter would be the main character. But there could also be her friends like Hermione and Ron. Hermione might encourage her artistic pursuits and help her research about magical art forms from old books. Ron could be a bit skeptical at first but then become her biggest supporter.
Voldemort could be one of the main antagonists. He could follow the female Harry Potter through the portal to Middle - earth, causing chaos there. Also, the orcs and other dark creatures from Middle - earth like the Nazgûl could be antagonists. They would oppose the female Harry Potter and the hobbits or dwarves she teams up with.
Voldemort could still be a main antagonist. Even if Fem Harry has a new inheritance, Voldemort would see her as an even greater threat. He might try to steal her inheritance or stop her from using it to defeat him. His Death Eaters would also be involved, trying to carry out his evil plans against her.
The nogitsune could also be a major antagonist. It thrives on chaos and mischief, and a powerful wizard like fem Harry Potter in its territory would surely draw its attention. It might try to possess her or use her magic for its own evil purposes.
One idea could be that fem Harry uses her charm and quick wits as a con artist to infiltrate the wizarding high society. She could pretend to be a powerful witch from a far - off land and con them out of valuable magical artifacts.
The Ministry of Magic could be the antagonists. Since Harry is in a gang, they might see him as a threat to the order of the wizarding world. They could send Aurors after him and his gang mates, trying to arrest them and break up the gang.
It could be Orochimaru. He's always been interested in power and the hunt for powerful things. He might see fem Naruto as a threat or a potential source of power. He could try to capture her or stop her from achieving her goals in the hunt.