One idea could be that a Lamia, a half - snake creature, secretly helps Harry Potter in the Forbidden Forest. Maybe she has unique knowledge of the forest's magic that can assist Harry in his quests.
A possible plot could involve a Lamia who has been cursed by a dark wizard. Harry Potter discovers her and tries to break the curse. In the process, they learn about the Lamia's culture and how it can be used to fight against the dark forces that are rising in the wizarding world.
Perhaps a Lamia character could be a new student at Hogwarts. She struggles to fit in because of her appearance, but Harry befriends her and they together uncover a mystery related to an ancient spell that is connected to her Lamia heritage.
One plot idea could be Fem Harry discovers a hidden lair of the Lamia. There, she forms an unlikely bond with a young Lamia who is an outcast among its kind. Together, they face the challenges of a world that fears and misunderstands the Lamia, while Fem Harry also has to deal with her own identity issues in the wizarding world.
One idea could be that Harry discovers a hidden Lamia community within the circus. The Lamia could be struggling to keep their existence a secret from the outside world while also dealing with internal power struggles. Harry, being the curious and kind - hearted character, gets involved and tries to help them find a balance.
One idea could be that Shikamaru, with his strategic mind, gets transported to the wizarding world of Harry Potter. He could use his intelligence to help Harry and his friends in their battles against Voldemort. For example, he might come up with unique battle plans that the wizards hadn't considered before, like using the environment in Hogwarts in unexpected ways during duels.
One idea could be that Bilbo's ring somehow ends up in the wizarding world of Harry Potter. Maybe it's discovered by a Hogwarts student on an archaeological dig during a school trip. Another could be that Bilbo is brought forward in time to Harry's era and he uses his hobbit stealth and Tookish curiosity to explore Hogwarts and help the trio in their fight against Voldemort. For example, his experience with Smaug could give him insights on how to deal with dangerous magical creatures.
A more complex plot could be that a magical experiment at Hogwarts goes wrong and opens a portal to Albedo's world. Albedo and some of the Hogwarts students, like Harry, Ron, and Hermione, cross over into Albedo's world. There, they discover that the alchemy in Albedo's world has the potential to either save or destroy the magic in the Harry Potter world. So they have to work together, with Albedo teaching them about alchemy and the Hogwarts students teaching him about magic, to fix the situation before it's too late.
One plot idea could be that a Kitsune disguises itself as a student at Hogwarts to learn more about human magic. It could get involved in Harry's adventures and use its Kitsune abilities, like shape - shifting or illusion - casting, to help or sometimes cause trouble. Another idea is that a Kitsune is a guardian spirit of an ancient magical place near Hogwarts, and Harry discovers it during one of his explorations. The Kitsune then becomes an ally or a guide for Harry in uncovering secrets about the wizarding world.
One plot idea could be that the original female character (ofc) is a new transfer student from a different magical school. She has unique magical abilities that Harry and his friends have never seen before. This leads to a series of adventures where they try to understand her powers and how they can be used against the dark forces. Another idea is that the ofc is a descendant of an ancient magical family that has been in hiding, and she brings knowledge of long - lost spells and artifacts to help Harry in his fight against Voldemort.
One idea could be that Ichigo is somehow transported to the wizarding world. He might use his Soul Reaper powers in unique ways against dark wizards. For example, his Zangetsu could be seen as a sort of magical weapon that even wizards are in awe of.
One idea could be that Maleficent, intrigued by the magic in the wizarding world of Harry Potter, decides to visit Hogwarts. She could end up teaching a special class on dark magic defenses, which would put Harry and his friends in an interesting situation as they learn from a very different kind of magic user. Another plot could involve Maleficent getting involved in the fight against Voldemort, either as an ally or with her own motives that might not be entirely in line with the Order of the Phoenix. Maybe she wants to use the chaos to gain more power for herself in the wizarding world.
One idea could be a time - travel plot where Harry somehow travels back in time and has to interact with Bellatrix in her younger days. This could lead to him trying to change her path before she becomes a Death Eater.