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.
Well, one possible plot could be that she discovers a hidden inheritance from her family that gives her new magical powers. Maybe it's an ancient magic that was long forgotten. This new power could help her in her fight against Voldemort in a way that the regular magic she had before couldn't. For example, she could have the ability to communicate with magical creatures on a deeper level and gain their assistance in battles.
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.
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.
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.
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.
Hermione would most likely be involved. She's Harry's best friend and would be eager to help him understand and manage his inheritance. She could use her vast knowledge of magic and research skills to uncover the secrets behind it.
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.
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.
It could be the Ministry of Magic. They have often been shown to be corrupt and self - serving in the original series. If they try to manipulate Harry again, he might see them as the main antagonists and target them in his revenge.
The Thalmor could be great antagonists. Their strict control over magic and their anti - human beliefs could put them at odds with Harry. They might see his different form of magic as a threat to their power in Skyrim.