It might be a new character introduced in the fanfiction. A young witch or wizard who discovers an ancient magic related to the oath of truth. This character could be from a different magical culture, like a wizard from the far east who comes to Hogwarts. Their understanding and use of the oath of truth could bring a new perspective to the Hogwarts community and help solve some long - standing mysteries in the wizarding world.
It could be Hermione. Since she values truth and knowledge so much, an oath of truth would be a significant concept for her. She might take the oath herself to prove the innocence of someone wrongly accused in the wizarding world, like Hagrid. And then use her wits and magical skills to fight against the false accusations.
It could be about a character in the Harry Potter universe taking an oath of truth that leads to various revelations. For example, a student might take this oath and then be forced to disclose secrets about a hidden magical artifact on the Hogwarts grounds. This could then set off a chain of events where other students and teachers get involved in the search for the artifact and the understanding of its power.
Hermione Granger might also be a main character. She is an important part of the original series and her intelligence and knowledge would be useful in uncovering any truths in this fanfiction. Also, Ron Weasley could be there as Harry's loyal friend, and together they could face the challenges related to the 'truth' in the story.
It could be that Dumbledore plays a more prominent role in this fanfiction. Since it's about 'the truth', perhaps Dumbledore has some secrets that are finally revealed, and he becomes a central figure in guiding Harry towards understanding. Additionally, some minor characters from the original series might be elevated to main characters if they hold key pieces of the truth.
Hermione Granger might also be a main character. Given her intelligence and thirst for knowledge, she could be researching the truth potion, its properties, and how to counter its effects if it's being misused.
There's also a possibility that it could be a minor character from the original series, like Neville Longbottom. He has grown a lot throughout the story. He might be the main character in this fanfiction, finally getting his own family after his heroics in the war. He could pass on his knowledge of Herbology to his children and create a family that is deeply involved in the study and protection of magical plants.
It could be a new character, perhaps a young witch or wizard who has just received their Hogwarts letter and then discovers this inheritance. This would be an exciting start to their magical journey.
Ron could be the main character in a Harry Potter polyjuice potion mishap fanfiction. Ron is known for his sometimes hasty decisions. He might be so eager to prove himself or get involved in some secret mission that he doesn't follow the potion - making instructions properly. This could lead to a mishap where he transforms into an unexpected person, and then has to navigate through the wizarding world in this new form, trying to hide his identity from his friends and family while also trying to reverse the effects of the potion.
It could be Harry himself. Maybe he's in a hurry to make the Polyjuice Potion for some important mission, like infiltrating the Death Eaters. But he messes it up and ends up looking like a really odd version of Voldemort, which causes all kinds of trouble and danger for him.
Maybe it's a new Slytherin character created specifically for the fanfiction. This character could be someone who has always admired Harry from afar and decides to take a chance on courting him. They might have different qualities from the typical Slytherins we know in the original books, being more open - minded and brave in their pursuit of Harry.
It could be about a new student at Hogwarts who discovers a truth - seeking orb in an old, forgotten corner of the castle. The orb reveals secrets about the founders of Hogwarts, which the student then has to decide what to do with. Maybe they face opposition from some teachers or older students who don't want these secrets out.