Well, it could work if there was some sort of magical interference or prophecy involved. For instance, a prophecy might have stated that Snape's daughter would have a role to play in the future of the wizarding world, and the Dark Lord might try to use Bella for his own ends. This would force Snape to protect her in secret, while Bella is oblivious to her true parentage. It would also create an interesting dynamic between Bella and the other characters, especially those who knew Snape well.
In this fanfic concept, it could start with Bella showing some unusual magical abilities that are not typical for a normal Muggle - born. Snape, being observant, starts to suspect that she might be related to him. As the story unfolds, he might find evidence that she is indeed his daughter. This discovery could lead to a transformation in Snape's character, as he now has a personal stake in protecting Bella. And for Bella, it would be a huge shock but also an opportunity to learn more about her true self and her place in the wizarding world.
One way it could work is through a complex backstory. Maybe Snape had a relationship before he became so deeply involved in the wizarding war. He could have met Bella's mother, and for some reason, Bella was raised away from him. In the fanfic, Snape could discover her true identity later. This would add a whole new layer of drama, as Snape is a very complex character with his own loyalties and secrets. And Bella, being a Muggle - born in the original story, this would change her entire backstory and connection to the wizarding world.
One way it could work is through some sort of dark magic manipulation in the wizarding world. Maybe a powerful dark wizard long ago used a spell to connect Bella's family line to Voldemort's in a very convoluted way. For example, a time - traveling dark wizard could have influenced Bella's ancestors to create this strange connection. However, it would be a huge stretch considering the different fictional universes of Twilight and Harry Potter.
Edward could be one of her allies. He could use his vampire abilities such as super - speed and strength to assist Bella in dangerous situations. His centuries - old knowledge could also prove invaluable in understanding the motives and actions of the CIA's enemies. Another ally could be Jacob. His shape - shifting abilities would give the team an extra edge in combat or in covert operations. He could also use his connection to the werewolf pack to gather information from areas that the CIA might not have easy access to.
The impact on the 'Harry Potter' universe would be significant. Snape's relationship with Dumbledore might be affected as he now has a daughter to protect. His role in the war could change as he tries to keep Bella safe from Voldemort. In the 'Twilight' universe, Bella's new identity could lead to new conflicts. For example, the Volturi might view her as a threat because of her wizarding heritage. And her friends in Forks would be in for a big surprise when they learn about her true nature. It would also introduce a whole new set of magical elements into the 'Twilight' world.
Well, a plotline could involve Bella being hunted by some sort of demon hunters who sense her devilish origin. Meanwhile, she tries to understand why her father was involved in hiding her true identity all this time. She could also have an internal struggle between the good in her, which was influenced by her human upbringing, and the evil tendencies that come with being the devil's daughter. There might be a prophecy about her that she has to either fulfill or fight against, and this could be intertwined with the Twilight universe's existing supernatural elements.
She might become more assertive. As the daughter of Ares, she would inherit some of his war - like traits. So, instead of being the somewhat passive Bella in the original story, she could be more proactive in making decisions and taking action. For example, she may no longer wait for others to protect her but instead take the lead in dangerous situations.
Well, Bella Swan as a SHIELD agent might bring some unique skills. Maybe her knowledge of the supernatural world in the Twilight universe could give her an edge in dealing with otherworldly threats that SHIELD sometimes encounters. She could be assigned to a special unit that focuses on such threats, using her past experiences to her advantage.
One way the storyline could be is that Percy uses his demigod powers to protect Bella from the various threats in Forks. For example, he could sense the presence of vampires and werewolves before Bella does and keep her out of harm's way. He might also introduce her to the world of Greek mythology, which would be a huge contrast to the world of Twilight she already knows.
It might not be as widely popular as some mainstream fanfic concepts. There are so many different fanfic ideas out there, and this one is rather niche. It depends on the specific fanfic community. For example, in the Twilight fandom, most fanfics revolve around the original vampire - human love story or its variations, so this devil - related concept may attract only a small subset of fans who are interested in darker and more out - of - the - box interpretations.
Well, one possibility could be that Bella Swan has to deal with the chaos that comes with being the Joker's daughter. Maybe she struggles to balance her normal life, like in Forks, with the dark and unpredictable world of her father. She might have some of the Joker's traits, like a wild sense of humor but also a bit of madness that she has to control.
Well, one possibility is that Bella's unique human nature attracts a Mikealson. Maybe her strong will, like in the original Twilight series, catches the eye of a Mikealson who is used to more submissive or less complex beings. They could start off as enemies, with the Mikealson initially seeing Bella as just another human to toy with, but then gradually fall for her unique charm.