It could be about Harry teaching his friends math in a magical way. He might turn equations into living creatures that demonstrate how they work. So, instead of just reading about quadratic equations, they see little gnome - like beings acting out the steps of solving it.
Perhaps in the fanfic, Harry finds that the ancient runes are actually a form of advanced math. He delves deep into the study of these runes, which are like magical equations. By understanding the math behind them, he unlocks new powers and secrets of the wizarding world that were previously unknown.
One possibility could be that Harry discovers the magic of math in his wizarding world. Maybe he uses math to solve some complex spells or potion-making ratios. For example, he realizes that a certain spell's effectiveness is related to geometric patterns and uses his newfound math knowledge to enhance it.
In this 'harry potter math fanfiction', it might also be that there is a new subject in Hogwarts called 'Magical Math'. The teachers could be magical creatures who are experts in both magic and math. The students would have to learn things like how to use equations to create spells or use geometric shapes to build magical structures. And there could be a big competition where the students use their math skills to win a great prize, like a magical artifact that can enhance their magic power.
It would show Harry as a more intellectual and curious character. His love for math could lead him to explore areas of magic that others haven't. For instance, he might use math to predict the movements of magical creatures, making him seem more of a wizard - scientist.
One possible plot could be that the Dursleys receive a threat from the wizarding world that they can only be protected from if Harry stays with them and helps. Harry, being a good - hearted person, decides to do so and in the process, he starts to understand them better and grows to love them.
One possible plotline could be that Harry discovers a magical doll during one of his adventures. This doll has some special power or connection to his past, and his love for it grows as he tries to figure out its mystery. Another could be that he starts collecting dolls as a way to remember his lost loved ones, and the dolls become a source of comfort for him in the dangerous wizarding world.
One possible plotline could be that Harry Potter discovers a new side of Fem Death that is not as menacing as she is often portrayed. Their relationship could start with a mutual curiosity and gradually turn into love as they get to know each other better.
One possible storyline could be that Harry discovers a magical plant that has the power to heal serious wounds. He then devotes his time to protecting this plant from dark wizards who want to use it for evil. This could lead to a series of adventures where he has to hide the plant in different magical locations and fend off attackers.
Maybe it's for a school play at Hogwarts. Harry is chosen to play a female character and has to wear a dress. His friends Ron and Hermione have different reactions. Ron might tease him at first but then support him when he sees how serious Harry is about doing well in the play. Hermione, on the other hand, helps him with his lines and how to act in the dress.
Perhaps the math genius gets recruited by a secret society within Hogwarts that is dedicated to exploring the connection between magic and numbers. They go on adventures to find magical artifacts that are said to be related to ancient math - based magic. Along the way, they face challenges from dark wizards who want to use this knowledge for evil purposes.
In a 'Harry Potter betrayed fanfic', perhaps Hermione turns against Harry. It could be because she disagrees with Harry's more dangerous and reckless plans to fight Voldemort. She might think he's endangering too many lives without proper thought, and this leads to a rift and a sense of betrayal.
One possible plot could be that Harry Potter, through some magical mishap or powerful spell, is transformed into a bride. Maybe he has to go on a quest to find a way to reverse the spell while dealing with the strange reactions of his friends and the wizarding world. For example, Ron might be completely confused and Hermione would be trying to find a solution in the library.