One possible plotline could be about Harry having special magical training from one of his teachers in a unique way that's not in the original books. For example, Professor McGonagall might teach him a very advanced form of Transfiguration in a more hands - on and personal setting.
In some fanfictions of this kind, it could be that a teacher, say Snape, has a change of heart towards Harry due to some unforeseen circumstances. They start to have more interactions outside of the classroom, and through these, Harry discovers a side of Snape he never knew. Snape might share some of his own past experiences with the Dark Arts and how he managed to resist the allure, which helps Harry in his own growth as a wizard.
Professor Snape is often very popular in such fanfictions. His complex character in the original series gives a lot of room for creative interpretations in fan works. Writers can explore his relationship with Harry in different ways, like having him be more of a mentor figure in ways that were not fully explored in the books.
One possible plotline could be the interaction between Harry Potter and a goblin in a unique magical situation that involves the use of lemon as a magical ingredient. Maybe the goblin has some secret knowledge about lemon's magical properties that Harry needs for a quest.
Well, perhaps there could be a plotline where the basilisk has some sort of connection to an ancient prophecy that Harry has to figure out. In this fanfiction, it might involve the basilisk being able to communicate in some strange way, leading to a whole new mystery for Harry to solve.
One interesting plotline could be a new adventure where Harry discovers a hidden lemon - themed magical object that has some unexpected powers. It might lead him on a journey to uncover the origin of this object and how it relates to the wizarding world.
Another plotline could involve Harry's inheritance being tied to an ancient wizarding family other than the Potters. This could cause a stir in the wizarding community as he has to navigate the politics and secrets of this new family connection while still dealing with his regular challenges at Hogwarts and against Voldemort's remaining followers.
A more complex plotline could involve the sister being targeted by Voldemort because he sees her as a threat to his plans. She might have a prophecy associated with her that predicts she will be the one to finally defeat him. This would put her in a lot of danger and force Harry to be even more protective of her while also relying on her unique skills to fight against the Dark Lord.
One possible plotline could be Harry learning different magical skills from each teacher in the harem. For example, he might learn advanced potions from one teacher and complex defensive spells from another.
One possible plotline could be a story where Pomona Sprout discovers a rare magical plant that has an unexpected connection to Harry Potter's past. This discovery could lead to a series of adventures as they work together to understand the plant's significance. Another could be a situation where Pomona helps Harry in his Herbology studies in a more in - depth way than in the original books, and a special bond forms between them through their shared love for plants.
One interesting plotline could be the twin sister using her unique bond with Harry to help him in his battles against Voldemort in ways that others can't. For example, she might have a special magical ability that is only enhanced by their twin connection.
Well, perhaps there's a story where Professor Vector and the characters in the 'Harry Potter' world find themselves in an alternate dimension due to one of Vector's experiments gone wrong. And they have to rely on Harry Potter's unique skills and Vector's knowledge to get back. There could also be a plotline about a time - traveling adventure involving them, where they go back in time to change an important event in the wizarding world's history.