A possible plot is that Bella, as a witch and doppelganger, is fated to be a key in a battle between good and evil witches. Her doppelganger form holds a special power that can tip the balance. She has to navigate through her new identity, make friends and enemies among the witch community, and decide which side she truly belongs to.
To develop Bella in this fanfiction, she could be given a mentor. Maybe an old witch who has been watching over her. With the mentor's help, she can learn about the history of doppelgangers in the witch world and how to control her powers. She can also struggle with the morality of using her powers, like whether she should use them to get revenge on those who have wronged her in the past.
A plot could revolve around Simon being a long - lost relative of Bella's. He shows up in Forks and his presence disrupts Bella's relationship with Edward. Simon has his own secrets about the supernatural world which Bella gradually uncovers, and she has to decide between the two different worlds she's now a part of.
Another plot idea is that Bella is sent to the Volturi as an emissary from the Cullen family for some reason. During her stay, she gets to know Jane better. Jane initially hates Bella for her association with the Cullens, but Bella manages to show Jane a different side of humanity and vampire - human coexistence. This could lead to a change in Jane's view of the world and a shift in the Volturi's policies towards the Cullens.
A possible plot for the 'Harry Potter and Bella Swan fanfiction' could be that Bella is actually a long - lost relative of a powerful wizarding family in the Harry Potter universe. When she discovers this, she travels to the wizarding world to learn more about her heritage. There, she meets Harry Potter, who is intrigued by her strange abilities. Together, they embark on a journey to uncover the secrets of her family's past and, in the process, they face challenges from those who don't want the secrets revealed. This journey could involve exploring ancient wizarding ruins, deciphering old spells, and facing off against dark forces.
A plot could revolve around Carlisle and Bella going on a secret mission together. Maybe they have to find a lost ancient vampire artifact that could change the future of the vampire world. Along the way, they develop a deep bond and respect for each other.
One idea could be that Bella, with her experience in the supernatural world from the Twilight series, somehow crosses paths with Chris Halliwell from Charmed. They could team up to fight a new kind of evil that combines the dark magic from the Charmed universe and the vampire - werewolf related threats from Bella's world. For example, a coven of vampires who have learned some dark spells.
Another plot could be that Bella Swan has a strange dream about Loki and then discovers she's pregnant. She's confused as she doesn't know how it's possible. Loki, in the meantime, senses a connection to her from afar. He travels to her world to find out more. As they meet, they realize that there's a greater force at work that has brought them together and they must figure out how to deal with the pregnancy and the implications it has for both their worlds.
Well, it's the contrast. In the original story, Bella is a normal human in a world of vampires and werewolves. As a witch in fanfiction, she becomes a force to be reckoned with. It's exciting to see her take control and use her powers.
One idea could be that Bella discovers her inner Ripper side when she is exposed to a powerful vampire's bloodlust-inducing power. She starts to struggle between her human morals and the new, dark desires.
One idea could be that Bella somehow gets transported to the wizarding world. She could be mistaken for a Muggle - born and sorted into Gryffindor due to her courage. Another plot could involve a magical artifact that links the two universes, and Harry and Bella have to work together to protect it from dark forces. Or perhaps Bella's vampire - like qualities in her own world are seen as a form of magic in the wizarding world, and she has to learn to control it with Harry's help.