Another plot twist might be that the Beast is not actually a 'beast' in the traditional sense. In the fanfiction, he could be a wizard under a false appearance curse, and Hermione discovers this. It changes the whole dynamic of their relationship because now they are both magic - users, and she has to figure out how to break the false - appearance curse rather than the typical Beauty and the Beast curse.
One interesting plot twist could be that the Beast is actually under a double curse. Not only is he a beast, but he also has a memory curse that makes him forget his true self. When Belle discovers this, she has to find a way to break both curses.
A great plot twist is when the objects in the castle, instead of just being there to serve as comical relief or side characters, are actually the ones who put the curse on the Beast in the first place, out of some misdirected sense of loyalty or protection. Also, Beauty could turn out to be a long - lost princess from a neighboring kingdom, and her union with the Beast has political implications that add a whole new layer to the story.
A great plot twist could be that the 'beast' is actually a dark wizard in disguise. He pretends to be cursed to lure in the 'beauty' who is a powerful young witch. But as the story progresses, she discovers his true identity and has to use her magic to defeat him instead of breaking a curse with love.
In some Beauty and the Beast pregnant fanfictions, a plot twist could be that the source of the Beast's curse is actually related to a prophecy about his future offspring. So, when Belle becomes pregnant, it sets off a chain of events that were foretold long ago. This could involve other magical beings coming to the castle to either protect or harm the baby. Another plot twist might be that Belle's pregnancy gives her the ability to communicate with the forest animals in a more profound way than before. They then become her allies in protecting the baby from any threats that may come from the dark corners of the enchanted forest.
One interesting plot twist could be that Belle actually has a hidden power that she discovers while in the Beast's castle. This power could be related to time-travel, which ties into the 'Back in Time' aspect. Maybe she can manipulate time to prevent certain events from happening in the past, like the Beast being cursed in the first place.
Perhaps a plot twist is that the Beauty is actually a parahuman with a power that she doesn't fully understand until she meets the Beast. Their connection then unlocks a new aspect of her power, changing the dynamic between them and their goals. For example, her power could be related to empathy, and the Beast's presence intensifies it to the point where she can influence the emotions of other parahumans around her.
One idea could be that Draco is cursed to be a beast and Hermione stumbles upon his enchanted lair while on a research mission. She initially fears him but then realizes there's more to him than his beastly exterior.
Maybe Hermione accidentally casts a spell that combines the story of Beauty and the Beast with their world. Harry becomes the 'beast' and Hermione starts to live in the same 'enchanted' area of Hogwarts as him. They gradually develop a deeper understanding of each other. As they explore the magic that binds them in this new situation, they also discover secrets about Hogwarts that were previously unknown.
Well, a common plot twist is the idea of soulmates. In some fanfictions, it is discovered that Hermione and Sirius are soulmates across different timelines or dimensions. This leads to their kiss as they are drawn to each other on a deeper level. Another plot twist could be a misinterpretation of prophecies. The fanfiction might have a prophecy that seems to point to Hermione and Sirius being together, which causes them to explore their relationship and end up kissing. Also, the idea of a parallel universe where the rules of the original story are different can lead to them kissing, such as a universe where age differences don't matter as much in relationships.
Often, a plot twist might involve Hermione uncovering a secret that Lucius has been hiding. This could be related to some dark magic he's involved in or a family secret. This discovery could then give Hermione some leverage over Lucius. Or perhaps there's a twist where other characters from the Harry Potter universe get involved. Like Harry and Ron coming to rescue Hermione, but she refuses to leave because she's in the middle of a complex plan to bring down Lucius from the inside.