One idea could be that the female Harry Potter arrives in Middle - earth with her magical abilities. She could use her magic to help the hobbits in their adventures, perhaps by using spells to protect them from the Black Riders. Another plot could involve her interacting with the wizards in Middle - earth, if there are any, and comparing and contrasting their magic systems.
Perhaps the Dark Knights could be on a quest to find a long - lost artifact that would give them ultimate power. Along the way, they face challenges from various Middle - earth races who oppose their goal. This could lead to epic battles and unexpected alliances. For example, they might encounter elves who are protecting the location of the artifact, and a complex power struggle ensues.
One idea could be a new character from our world being magically transported to Middle Earth and having to navigate the complex politics between different kingdoms. This character could have a special ability that is unheard of in Middle Earth and that ability could either be a great advantage or a source of trouble.
Well, a really cool plot idea would be if the OC was sent to Middle Earth and accidentally became part of a dwarf caravan. They'd have to learn the ways of the dwarves quickly and help them on their journey, perhaps to reclaim Erebor. And then there's the idea of an OC being sent to Middle Earth as a messenger from another dimension. This OC has to find Gandalf and tell him about a coming threat that even Sauron might not be aware of, which could completely change the course of events in Middle Earth.
Another plot idea might be that a female Harry discovers a new form of magic that is more accessible to female witches. This could lead to her having to hide it from the male - dominated wizarding society at first, and then later using it to change the way magic is taught and practiced at Hogwarts.
One plot idea could be that the female Voldemort has a change of heart. Maybe she starts to see the error of Voldemort's ways after interacting with Harry Potter. She could start to secretly help Harry and his friends against the Death Eaters, which would create a lot of internal conflict within the Dark side.
Maybe the female kitsune is an ancient magical being who has been asleep for centuries. Harry stumbles upon her while exploring an old, forbidden part of the Hogwarts grounds. She wakes up and initially doesn't understand the modern wizarding world. Harry helps her adapt and in the process, they develop a deep friendship that could potentially turn into a romantic relationship as they face various challenges together, like dealing with the Ministry of Magic's suspicions about the kitsune.
Well, perhaps Harry would be super confused at first. He'd find himself in a world full of different races like hobbits, elves, and dwarves. Maybe he'd use his magic to help in the fight against Sauron. He could teach the people of Middle - earth some new spells or ways of magic that they've never seen before.
One possible plot could be that Harry Potter somehow gets transported to Middle Earth. He might use his magic skills to help in the battles against the dark forces there. Maybe he forms an alliance with the Fellowship of the Ring and uses his knowledge of facing dark wizards like Voldemort to take on Sauron.
One interesting plot twist could be that when Harry Potter apparates to Middle - earth, he discovers that the magic there is so different from his own that he loses his ability to perform some of his usual spells. This forces him to adapt and learn Middle - earth magic, creating a whole new set of challenges for him.
A great plot idea would be a crossover with 'Game of Thrones'. The political intrigue in both worlds could be merged. Maybe Talion could find himself in the middle of the power struggle between the different houses in Westeros. He could use his skills to either side with a particular house or try to stay neutral while still achieving his own goals in Middle Earth which are now somehow intertwined with the events in Westeros.