Well, it could be related to a potion. There are potions in the wizarding world that can affect memory. If she drank the wrong potion, either by accident or because someone tricked her into it, she could forget she was a witch. Also, it's possible that some kind of ancient magic or a magical artifact had an unexpected effect on her. For example, if she came into contact with a cursed object that was designed to steal or distort memories, it could cause her to forget her witch - like nature.
One possible reason could be a spell gone wrong. Maybe she was experimenting with some new magic and it backfired, causing her to forget she was a witch. Another reason could be some kind of magical amnesia brought on by a powerful dark force or a magical accident.
Perhaps she was hit with a memory - altering charm by an enemy. In the wizarding world, there are many dark wizards and witches who might want to target Hermione because of her intelligence and power. They could use a charm to make her forget she was a witch so that she would be less of a threat. Or it could be due to a self - inflicted curse. Maybe she was trying to forget something traumatic related to her magic and accidentally made herself forget her entire magical identity.
In such a fanfiction, it could lead to some really interesting character development. For example, her friends, Harry and Ron, would have to find a way to help her remember. They might start by showing her simple spells and waiting for her old self to resurface. Hermione, on the other hand, would initially be in disbelief and might even think they are playing some elaborate prank on her. This could create a lot of comical as well as heart - warming moments in the story.
In a fanfiction where Hermione forgets she's a witch, it would be a huge disruption to the normal order. She has been such an important part of the wizarding world. Her forgetfulness could mean that she no longer has the confidence she once had. She might start to doubt herself and her place in Hogwarts. This could lead to her being bullied or taken advantage of by some of the less - friendly characters. However, it could also be a chance for her to grow in a different way, perhaps by relying more on her non - magical skills and learning about the wizarding world from a completely new perspective.
The Hogwarts faculty would surely notice her strange behavior. Professor McGonagall might be the first to suspect something is wrong. She could try to perform diagnostic spells on Hermione, but since the cause of her forgetfulness is not a typical magical ailment, it might be difficult to figure out. Meanwhile, Hermione would be struggling to fit into the wizarding world she no longer remembers, which could lead to some awkward and funny situations.
One possible reason could be jealousy. Maybe she sees the Weasleys as getting things too easily in the wizarding world compared to her own hard - earned achievements. For example, they have a big family support system that she lacks, and she might envy that.
It could be a way for writers to show their creativity. By taking a well - known relationship and flipping it on its head, they can create unique and unexpected storylines. Maybe they want to explore how Ron would react to Hermione's hatred and how it would change his character development. Also, some fans might have their own personal interpretations of the characters that deviate from the original, leading them to write such fanfiction.
In fanfiction, Hermione could face challenges in the Muggle world as a witch. She might struggle with not being able to use magic openly like she can in the wizarding world. This could lead to some really interesting character development, like her learning to rely more on her intelligence and non - magical skills. She could also have some hilarious misunderstandings with Muggles when they notice something a bit off about her actions that are actually influenced by her magical nature.
It could also be that they are used to Stiles being the one who takes care of them and remembers things for them. He's always been the planner and the one to keep things in order. So they unconsciously assume that he doesn't really care about his own birthday as much as he does about helping them, and they forget all about it.
Maybe he was hit by some magic or a spell that affected his memory. It could also be due to some sort of trauma he experienced that made his mind block out his memories of Annabeth.
Perhaps Snape realizes that Hermione is often a target because of her Muggle - born status. In the wizarding world, there's a lot of prejudice against Muggle - borns. Snape, having experienced his own share of hardships and being an outcast in some ways, might empathize with her situation and thus be protective. Also, her friendship with Harry Potter might make Snape more watchful over her, as Harry is always in the center of many dangerous situations and Hermione is closely associated with him.
There's also a fanfiction where Hermione, as a born witch from Groves, gets involved in a time - travel mystery. She has to rely on her natural witch abilities to solve the mystery and set things right. It's a thrilling read as it combines her character traits like her determination and cleverness with the unique setting of Groves.