Well, perhaps in this fanfiction, Harry Potter uses his magical skills in the context of auditing. He could use spells to detect financial irregularities, like a magical version of auditing software. For example, he might cast a spell that reveals hidden transactions in a company's books.
One possible antagonist could be a corrupt wizard in a high - ranking position in the Ministry of Magic's financial department. This wizard might be trying to cover up his misdeeds and would see Harry as a threat to his scheme.
Harry Potter could also be a popular character. He might be the one who discovers the need for an auditor in the first place. Maybe he stumbles upon some strange financial activities in the wizarding world and decides to bring in an auditor to get to the bottom of it. His courage would be useful in protecting the auditor from any threats.
There might be a fanfiction where an auditor from the Muggle world somehow stumbles into the wizarding world. They start auditing Hogwarts' accounts, which are a complete mess due to all the magical expenses and ancient spells that have financial implications. This could be a humorous story as the auditor tries to make sense of wizarding currency and magical accounting.
Well, perhaps the Yautja is on a hunt in its own world but gets caught in a magical portal that leads it to Hogwarts. The students are both scared and intrigued. Hermione starts researching about it, trying to find a way to send it back. Meanwhile, the Yautja sees the Death Eaters as worthy prey and starts stalking them. Harry has to convince the Yautja not to go on a full - out killing spree which might endanger innocent lives as well.
A possible plot could be that a Smilodon escapes from a magical menagerie in the Forbidden Forest. Harry and his friends discover it and try to return it safely without getting hurt or getting in trouble with the Hogwarts authorities.
Perhaps Harry could be a wizard - geisha hybrid. He might use his magic to enhance the traditional geisha arts, like creating magical illusions during his performances. He could be in a Hogwarts - like school but also trained in the ways of the geisha, with spells and potions being used in the context of geisha traditions.
Well, one possible plot could be that Orochimaru somehow finds his way into the Harry Potter universe. He might be interested in the unique magic there, like the Elder Wand or the Philosopher's Stone. He could try to use his ninja skills and devious ways to steal these powerful magical items, and Harry and his friends would have to stop him using their own magic.
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.
A possible plot could be Morgoth's return in a weakened form in the Forbidden Forest. His presence starts to corrupt the magical creatures there. Harry and his friends sense the disturbance and go to investigate. They soon realize it's a much greater threat than they thought and must find a way to either banish Morgoth back to his realm or destroy his essence completely.
One possible plot could be that Harry and Ginny go to a secluded wizarding cottage by the sea. They spend their days exploring the nearby magical creatures and hidden coves. At night, they sit by the fireplace and share stories from their Hogwarts days, strengthening their bond even more.