One creative plot twist could be that the once - Grimm - turned - human has memories of their Grimm past. This could lead to internal struggles as they try to come to terms with the evil they once represented. For example, they might have nightmares about their former life as a Grimm and be haunted by the actions they took. Another twist could be that they have special powers related to their Grimm origin. Maybe they can still communicate with Grimm in a way, but use this ability to protect humans instead. It adds an interesting dynamic to the story.
Perhaps the Grimm - turned - human discovers that they are the key to a long - forgotten prophecy. Their transformation was not an accident but a necessary step in a grander scheme. This could involve them having to make sacrifices for the greater good, like giving up their new - found humanity to stop an even greater threat. Or, they might find out that there are others like them, but they are being hunted down by an unknown force that wants to prevent the prophecy from being fulfilled.
I think Jaune could be a likely candidate. He's a main character with a lot of development potential. His insecurities and his strong will to become a better Huntsman could be twisted if he were turned into a Grimm. It would create a great internal conflict as he battles his new nature.
One idea could be a character who is turned into a Grimm due to a failed experiment. They then have to struggle with their new form and inner Grimm instincts while still having memories of their human life. Another could be a human turned Grimm as a result of a dark magic spell, and they try to find a way to reverse it while being hunted by other Huntsmen and Grimm alike.
Some characters might be very distrustful. After all, Grimm are seen as pure evil in the RWBY world. They would be cautious around the Grimm - turned - human, constantly watching for any signs of the old Grimm nature to resurface. For instance, Ruby might be hesitant but also curious. Her kind nature might make her want to give the new human a chance, but her experience with Grimm would keep her on guard.
One possible plot twist could be that the characters raised by Grimm end up being the ones to save the RWBY world. Despite their upbringing, they develop a sense of justice that is different from the norm. Another could be that they have a hidden power that is related to their Grimm - raising, which gives them an edge over the regular Grimm.
There's also a fanfic that delves into the idea of humans being able to control Grimm. In this fanfic, a group of special humans have the power to communicate and direct Grimm. It shows how this new ability changes the power dynamics in the RWBY world and the moral dilemmas that come with it. For example, should they use the Grimm for good or will the power corrupt them?
In some fanfictions, there might be a plot twist where the Aburame's symbiotic relationship with bugs was actually a result of an ancient magical experiment gone wrong in the Potterverse. This would completely change the understanding of both the Aburame clan and the magic in Harry Potter. Also, a plot twist could be that the Hogwarts houses have a hidden connection to the Aburame clan's way of life. Maybe Gryffindors could learn to be as stealthy as the Aburame through some special training involving the bugs.
One creative plot twist could be that Peter, after turning into Carnage, retains his moral compass. So instead of going on a rampage, he uses the Carnage symbiote's powers for good. For example, he might be able to heal people with the symbiote's tendrils in a new and unexpected way.
A really cool plot twist in a change - of - pace Death Note fanfiction might be if the Death Note's power is transferred to an inanimate object. So instead of a person writing names, it's an object that has the ability to kill. This could lead to a lot of chaos as people try to figure out how to stop it. Another plot twist could be that there is a second type of Death Note that has completely opposite rules. For example, instead of killing people, it can bring them back to life, but with a catch. This would completely change the moral and power dynamics in the story. And finally, if the characters in the Death Note world discover that they are actually in a simulation and that someone outside is controlling their fates, that would be a mind - blowing plot twist that would change everything.
Well, here's a plot twist. When they swap bodies, they also swap some of their chakra natures partially. So Sakura, who is used to her own chakra control for her medical ninjutsu and strength - based attacks, now has to deal with Hinata's more refined and gentle chakra control. This makes her medical ninjutsu even more precise but also makes her struggle with using Hinata's chakra for combat. Meanwhile, Hinata in Sakura's body has a boost in physical strength but has to learn how to control it properly without overdoing it. It changes the way they interact with their teammates and how they are perceived in the ninja world.
Perhaps Naruto is initially unable to control Godzilla properly when he first summons him. This causes chaos as Godzilla goes on a rampage, but Naruto then has to figure out a way to communicate with Godzilla on a deeper level to stop the destruction and turn him into an ally. This adds a layer of complexity and character growth to the story.