Perhaps they go on a journey to find out more about their relationship's origin. They might travel to different vampire clans around the world to seek answers, facing all kinds of adventures and challenges along the way, and in the process, their bond grows even stronger.
One plot idea could be that Bella discovers she has a special power that only Alice can understand and help her develop. This power could be related to seeing the future in a different way than Alice does, creating an interesting dynamic between them as they try to figure out how it works.
One idea could be that Harry discovers a hidden magical connection to the vampire world through Alice. Maybe Alice has a premonition about Harry's role in a new, greater threat that involves both the wizarding and vampire realms. They then have to work together to figure out how to stop it.
Perhaps they get trapped in a time - loop. In this scenario, they have to figure out how to break free while also dealing with their complex relationships. Each time they go through the loop, they learn something new about each other and themselves, which helps them in their overall mission to escape the time - loop.
One idea could be that Harry discovers a hidden portal that leads him to the Twilight world where he meets Alice Cullen. They then team up to fight a new dark force that is threatening both their worlds.
A plot could revolve around Hermione being transported to the Twilight universe and Alice taking her under her wing. They could then learn from each other. Hermione could teach Alice about magic, and Alice could show Hermione how to navigate the complex social structure of the vampires. This could lead to them forging a strong friendship and facing challenges together, like dealing with some of the more hostile vampires who don't trust Hermione.
One idea could be that they have to overcome the differences between their two worlds. Bella being from her normal human world and Laurent from his vampire one. They might struggle with how their relationship is seen by others, like the Cullens.
A great plot idea is Bella exploring her newfound powers during pregnancy. Since she's already had some unique experiences as a human in a vampire - filled world, pregnancy could enhance or bring out new abilities. Maybe she can communicate with the unborn child in a special way that no one else can understand. This could lead to some interesting scenarios where the baby gives her clues or warnings about upcoming events. Also, the family could be divided on how to handle these new developments, some seeing it as a great opportunity while others as a potential danger.
One interesting fanfiction could be about Bella and Alice going on a shopping spree together in a human - vampire friendly town. They could bond over choosing outfits and sharing fashion tips, which is quite different from the usual intense situations in the original series.
A more character - centric plot could be about Rosalie and Bella finally coming to a true understanding and friendship. Alice could be the catalyst in this, arranging situations where they have to work together and learn about each other's pasts. This could include Rosalie sharing her human life story with Bella, and Bella sharing her fears and hopes for her new vampire life.
One plot idea could be a story where Bella, Rosalie, and Alice have to work together to solve a mystery in the vampire world. Maybe there's a new threat that only their combined skills can handle. Another could be a story focused on their friendship, like a road trip where they discover new things about each other and themselves. Or perhaps a story where they use their powers to help humans in a small town without revealing their true nature.