Maybe the Witch OC is from a family that has a long - standing feud with one of the major wizarding families in the Harry Potter universe. Her presence at Hogwarts stirs up old tensions, and she has to navigate through this while also dealing with the normal Hogwarts drama like exams and Quidditch. She might initially be seen as an outsider but eventually forms her own group of friends.
Another plot could be that the Witch OC discovers a hidden chamber in Hogwarts that has been forgotten for centuries. Inside, there are ancient spells and artifacts. She teams up with Harry, Hermione, and Ron to figure out what the chamber is all about. Along the way, they face challenges from other students who are jealous of their discovery and also from the secrets hidden within the chamber which seem to have a connection to the dark history of Hogwarts.
One idea could be that the Witch OC is a transfer student from a far - off magical school. She has unique magical abilities that are rare in Hogwarts, like the ability to communicate with magical creatures on a deeper level. This could lead to her helping Hagrid with some of his more difficult creature - related tasks and catching the attention of Harry and his friends.
Maybe the Scarlet Witch travels back in time to the era of Harry Potter. She could end up at Hogwarts and teach the students some new magic based on her powers. The students, especially Harry, would be fascinated by her different style of magic. They could team up to protect the school from an ancient evil that is awakened by her arrival in the past.
A plot could involve a group of witch hunters infiltrating Hogwarts. They think there are dark witches there, but they end up getting lost in the magical castle and start to see the beauty and positive aspects of magic. As they interact with students and teachers, they have to re - evaluate their views on witches and magic in general.
One idea could be a magical competition between Hogwarts and Cackle's Academy. Students from both schools could compete in various magical tasks, like a complex potion - making duel or a dangerous magical creature taming challenge. This would bring together the worlds of Harry Potter and The Worst Witch in a really exciting way.
Perhaps Aunt Petunia is a witch who was cursed long ago. The curse made her forget her magic and act like a Muggle. When Harry unknowingly breaks the curse, she suddenly has her powers back. She then has to face the wizarding world again and deal with all the changes that have occurred since she last remembered her true self. She might even have some unique powers that are different from the norm because of the curse.
A possible plot is that the Gaunt OC is an outcast within the family due to their different views on magic. They believe in a more inclusive form of magic that accepts all wizards and witches regardless of blood purity. So, they run away from the Gaunt family and end up at Hogwarts. There, they face discrimination from some Slytherins who know of their family name, but they find friends among the other houses and together they try to change the perception of blood purity at Hogwarts.
Another plot could be that the OC is an outcast in the wizarding world due to their unorthodox magical abilities. They see Harry as a kindred spirit. When they adopt him, they take him on a journey to discover the true nature of magic, which is different from what is taught at Hogwarts. This could involve exploring hidden magical realms and learning from magical creatures that are not well - known in the wizarding community.
One idea could be a male oc who is a transfer student from a different wizarding school. He has unique magical abilities that are rare in Hogwarts, like the ability to communicate with magical creatures on a deeper level. This could lead to him helping Hagrid with some of the more dangerous creatures and getting into all sorts of adventures around the Forbidden Forest.
One idea could be that the OC is a transfer student from a far - off magic school. The harem could consist of characters from different houses. For example, Hermione could be attracted to the OC's vast knowledge of ancient magic that he or she learned from their original school. Ginny might be drawn to the OC's brave and adventurous spirit, similar to Harry's. And Luna could be interested in the OC's unique view of the magical world, which is different from Hogwarts' norm.
Well, a great plot idea could be that the mermaid OC has the power to communicate with magical creatures that live in the lake and around Hogwarts. When some strange and dangerous creatures start to act up, she warns Harry Potter. They then team up to figure out what is causing the creatures to behave this way. Maybe it has something to do with a dark spell cast by Voldemort's followers. Or perhaps the mermaid OC falls in love with a Hogwarts student, and they have to face the challenges of a relationship between a mermaid and a human - like in the classic mermaid tales, but with a Harry Potter twist.
One idea could be that the OC is a foreign exchange student who has unique magical abilities unknown to Hogwarts. They could help Harry in the Triwizard Tournament tasks in unexpected ways, like using ancient spells from their home country.