One interesting Bella's brother Twilight fanfiction could be where he has some sort of hidden power that he has to keep secret from everyone in Forks. Maybe he can communicate with the animals in a way that's different from the werewolves in the story.
Another great Bella's brother Twilight fanfiction idea could be that he discovers the truth about the Cullens much earlier than Bella does. And instead of being scared, he is intrigued and starts to study vampires on his own. He could even find some old texts or legends that give him more insight into the vampire world, and this knowledge could be used to help the Cullens or protect Bella in a different way.
One great 'Twilight Bella is alpha' fanfiction could be 'Bella's Alpha Ascent'. In this fic, Bella discovers her inner alpha strength in a really unique way. It might show her leading the pack in a new way, different from the normal Twilight dynamics.
One interesting Bella and Charlie fanfiction could be where Charlie discovers Bella's vampire side in a more comical way. For example, he walks in on her using her super speed to clean the house and just stares in shock.
One interesting 'bella is blind' fanfiction could be where Bella's blindness adds a new layer to her relationship with Edward. Maybe he has to use his vampire senses in a different way to protect her. For example, he might rely more on his sense of smell to detect danger around her since she can't see it coming.
Some fanfictions could revolve around the idea of baby Bella having a special connection to the supernatural world right from infancy. This could lead to all sorts of adventures and unique storylines that deviate from the original 'Twilight' plot. For instance, she might have some sort of premonition ability as a baby that the other characters have to figure out.
There could also be a fanfiction where the kiss is a dare or a result of some sort of game. For example, the Cullens and Bella are playing a truth or dare - like game among themselves, and when it's Alice's turn, she chooses 'dare' and is dared to kiss Bella. This could lead to a whole new exploration of their relationship and how the other Cullens react to it.
One common plotline could be Bella getting injured in a way not shown in the original Twilight series and Edward being overly protective in the hospital setting. For example, she might be in a car accident on her way to visit Jacob and end up in the hospital. Edward would then be by her side constantly, causing some tension with the werewolf pack who also want to check on her.
One popular fanfiction could be about Bella using her vampire abilities to protect Edward from some new supernatural threat in Forks. Maybe she has to face a powerful vampire coven that has a vendetta against the Cullens, and in the process, her relationship with Edward deepens in new and unexpected ways.
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 great 'Twilight Bella Daughter' fanfiction could be 'The Daughter of Bella and Edward's Unseen Adventures'. It might explore the daughter's unique powers and how she navigates the vampire - human - werewolf world. Another could be 'Bella's Daughter: A New Era in Forks' which could focus on her bringing new changes to the town of Forks while dealing with her own identity.
One popular Bella and Jacob Twilight fanfiction might be those that explore an alternate ending where Bella chooses Jacob instead of Edward. In these stories, the author delves into how their relationship would develop, how the werewolf pack would react, and how the Cullens would handle the situation.