The main characters would be Naruto, who brings his ninja - like abilities and unique personality from his own series. Then there are the Cullens - Edward, Carlisle, Esme, etc. - each with their own vampire abilities and family dynamics. And of course, Bella, who is a central figure in the Twilight series. In this fanfiction, they are all likely to be involved in some sort of story arc together, probably with Naruto having some sort of impact on the relationships and situations involving the Cullens and Bella.
I'm not sure exactly as it could be many things. It might involve Naruto characters interacting with Twilight's Cullen family and Bella in a negative or critical way. Maybe it's about Naruto characters getting involved in the drama of the Twilight world and having some sort of conflict with Bella and the Cullens.
There could also be side characters like Sakura from Naruto. She might be jealous of Bella if there is some sort of romantic undertone between Naruto and Bella. In Bella's world, characters like Jacob could also be part of the fanfiction. Jacob's werewolf nature could be an interesting element when combined with the ninja world, and he could interact with Naruto in different ways depending on the plot.
Obviously, Edward Cullen and Bella Swan are the most important. Edward, the vampire, is central to the story as Bella's groom. Bella, the human - turned - vampire - later in the original series, is the bride. Then there's Alice Cullen. She is often a key character as she loves to plan events and would be all over the wedding preparations. Jasper Cullen might also be important as he could help keep the emotions in check during the big day. And of course, Charlie Swan, Bella's father, his presence or his thoughts about the wedding could be a significant part of the fanfiction.
Esme Cullen, the matriarch of the Cullen family, would surely be part of the story. She would be very nurturing towards Bella during her pregnancy. Jasper Cullen might also be included, perhaps using his power to influence the emotions of those around Bella to keep her calm during the pregnancy. And of course, there could be other minor characters from the Twilight universe popping up in the fanfic.
I would recommend 'A New Beginning for Bella and Edward'. This fanfic takes their story in a different direction after the events in the original series. It shows how they handle new challenges together and the growth of their love in the face of those difficulties. There are some really beautiful and heart - warming moments in it.
Hermione is likely to be the central character through which the story unfolds. She will be the one experiencing the Cullen world. Alongside her, Edward Cullen could be a major character as he is often a central figure in Cullen - related stories. His special ability to read minds might create interesting interactions with Hermione, who is very intelligent and has her own complex thoughts.
The popularity of Bella Cullen and Edward Cullen fanfiction comes from the fact that fans were so in love with their relationship in the original books. People wanted to explore more of what could have been, or different scenarios for them.
His parents or adoptive parents in the Cullen family are likely to be main characters as well. They would be responsible for taking care of baby Edward, so they play an important role in the fanfiction.
Often, antagonists are also important characters in jasper hale and edward cullen fanfiction. These could be rival vampire clans or individual vampires with malicious intents. They create conflict for Jasper and Edward, forcing them to use their powers and work together. The presence of these antagonists can drive the plot forward and also show different aspects of Jasper and Edward's personalities as they face these threats.
There could be a female character, Sofia, who is another member of the mafia. She sees Bella as a threat at first, thinking she'll steal her position or the attention of the men in the mafia. But as time goes on, they might form an unlikely alliance. There may also be a young and ambitious mafia underling named Antonio, who is always looking for ways to climb the ranks and his actions often impact Bella's situation in the story.