A possible plot twist could be related to her powers. If Percy had certain powers before, they could be altered or enhanced in unexpected ways after reincarnation into a girl. For instance, her physical strength might be combined with a new kind of magical ability that is unique to female characters in that fictional universe. Also, there could be a twist where she discovers a hidden connection to a female - only group or prophecy that she was unaware of as Percy. This could lead her on a whole new adventure and change the direction of the story.
Her personality might become more empathetic. As a girl, Percy could be more in tune with the emotions of others around her. For example, she might be quicker to notice when someone is sad or in need of help. In her previous life, she might have been more focused on her own goals and adventures, but now she could be more nurturing.
Definitely. One type of Percy is reincarnated fanfiction could involve him coming back as a different species. Maybe he's reincarnated as a faerie or a magical creature. In these stories, he often has to learn about his new form and how to survive in a world that may be very different from what he knew before.
One common theme is identity. Percy has to figure out who he is in his new life. Is he still the same hero? Another theme is redemption. Maybe he made some mistakes in his past life and his reincarnation gives him a chance to make things right.
One great 'Percy Jackson is Reincarnated' fanfiction is 'Reincarnated Hero'. It has an interesting take on Percy coming back in a different era and having to deal with new challenges while still having his old memories and powers. The author does a wonderful job of portraying Percy's character growth in this new situation.
It could be an old enemy from Percy's past life who has also found a way to be reincarnated. This enemy might hold a grudge against Percy for something that happened in their previous encounter and is now seeking revenge in this new life.
Another plotline could be that Percy's reincarnation is part of a grand plan. There could be a powerful being or a prophecy that dictates his reincarnation. When he is reborn, he is fated to either save or destroy this new world he is in. Along the way, he meets friends from his past life who have also been reincarnated, but they don't recognize each other at first, and they have to go through a series of adventures together to remember who they really are.
One popular trope is memory recovery. In many of these fanfics, Percy has to gradually remember his past life as a demigod. It adds an element of mystery and character exploration as he figures out who he was. Another is the 'fish out of water' situation. Since he's reincarnated, he often has to adapt to a new world or time period, which can lead to some really interesting and comical situations.
Make the character have flaws that are relatable. Maybe the reincarnated character is overly confident from their past achievements in their previous life, and this overconfidence often gets them into trouble in the dangerous world of demigods. They have to learn to be more humble and work with others, which is a great character arc.
It would be an amazing experience. You'd have incredible powers, like being able to control the elements or manipulate time. You could interact with all the beloved characters from the Percy Jackson universe in a whole new way. Maybe you'd be a new god, bringing in fresh ideas and changes to the pantheon. And you'd get to see the world of Camp Half - Blood and the other mythical places from a divine perspective.