One common plot twist could be that Bella's assassin skills are discovered by the Volturi, who then try to either recruit her or eliminate her because they see her as a threat to their power. Another might be that Bella discovers a secret society of assassins within the Twilight universe that has been manipulating the events all along, and she has to decide whether to join them or fight against them.
Often, a plot twist might involve the nature of the baby. In some fanfictions, the baby could have powers that are not just a combination of vampire and human, but something entirely new. It could be a power that is so strong it attracts other supernatural beings, not just vampires. This would change the dynamics as Bella and Edward would have to protect the baby from new threats.
One common plot twist is that Bella's mermaid identity is revealed in a very unexpected way. Maybe during a swim with the Cullens, she suddenly transforms, shocking everyone. Another is that her mermaid powers are somehow connected to the Volturi's plans, adding a new layer of danger.
One common plot twist is that Bella might be in danger not just from the typical vampire threats but from a human organization that knows about vampires. Edward then has to save her while also hiding the existence of vampires from this group. For example, in some fanfics, there are hunters who target Bella to get to Edward, and Edward has to outwit them.
Well, one common plot twist could be that the kidnapper is actually a long - lost relative of Bella's with a hidden agenda. Another might be that the kidnapping was a set - up by a jealous vampire from another coven who wants Edward for themselves. And sometimes, it could turn out that Bella has some sort of hidden power that the kidnapper is trying to either use or suppress.
One common plot twist could be that the kidnapper is actually a character who was thought to be dead in the original Twilight series. This sudden revelation can completely change the direction of the story.
One interesting plot twist could be that Bella's transformation into a vampire gives her a unique power that no other vampire has. For example, she might be able to control the weather. Another twist could be that instead of joining the Cullen family right away, she runs off on her own to explore the vampire world. Maybe she discovers a whole new coven that has different values and ways of life compared to the Cullens.
One interesting plot twist could be that Bella, as a new vampire, discovers she has unique powers that no other vampires have. For example, she might be able to control the elements in some way.
Well, a plot twist might be that the baby has a special connection to an ancient vampire clan that no one knew about. This could lead to a whole new storyline where they try to claim the baby. Also, Bella could experience a vision during the birth that reveals a future event that changes the course of the 'Twilight' world. Maybe she sees a great war coming and this knowledge makes everyone around her change their plans. It could also be that the baby's birth causes some sort of magical ripple effect that starts to change the abilities of other vampires in the area.
Another possibility is that Edward betrays Bella by revealing her secrets to their enemies. Maybe he was forced to do so under some sort of blackmail from a powerful and malicious vampire or other supernatural being. In this case, Bella would have to face the consequences of having her secrets exposed while also dealing with Edward's betrayal.
One common plot twist could be that the kidnapped character discovers they have a special power that the vampires didn't anticipate. For example, they might be able to resist the vampires' mind - control powers more than expected. Another could be that there is a secret alliance among some of the vampires that the main characters are unaware of, and this alliance either helps or hinders the kidnapped character's situation. And sometimes, the kidnapped character turns out to be related to one of the vampires in a way that changes the whole dynamic of the story.