Sometimes, in this type of fanfiction, a vampire who has a grudge against Edward might become an antagonist. This vampire could see Bella as a way to get back at Edward, either by trying to turn her against him or by directly attacking her. Another possible antagonist could be a powerful vampire who wants to use Bella for her new and unique powers after she is turned.
Often, other vampire clans that oppose Bella's transformation can be the main antagonists. They might see her as a threat to the vampire world order. For example, a traditionalist clan that believes humans should not be turned so easily could try to harm Bella or drive her away from Edward.
In some stories, it could be a group of vampires who are jealous of the relationship between Edward and Bella. They might try to break them apart by causing trouble for Bella as she adjusts to being a vampire. They could spread rumors about her in the vampire community or try to make her life difficult in other ways, like blocking her access to resources that new vampires need to survive and adapt.
The Volturi could be antagonists. They are the powerful vampire coven that enforces vampire laws. Since Bella's transformation might not follow the normal protocol, they could see her as a threat to their order. They might come after her to either destroy her or bring her under their control.
In some cases, there could be a new vampire or a shape - shifter who enters the prison and has a vendetta against Edward or Bella. This character would then be a major antagonist, constantly trying to harm them and prevent them from achieving their goals of getting out of prison or finding justice.
Maybe there are some powerful and corrupt humans in the gang wars. They are not afraid of vampires and want to take over the territory that Edward's family has been protecting. These humans could be the main antagonists as they constantly create trouble for Bella and Edward.
In some fanfictions, other vampires outside the Volturi who oppose Bella and Edward joining the Volturi could be antagonists. They might fear that Bella and Edward's new alliance will give the Volturi too much power. These vampires could then plot to stop Bella and Edward from fully integrating into the Volturi.
It could be the Volturi. Since the baby is a vampire - human hybrid, the Volturi, who are very strict about vampire laws, might see the baby as a violation of their rules and try to eliminate it.
Well, a common plotline is Bella's discovery of new vampire senses. In fanfiction, it could be that she discovers she has a unique sense that other vampires don't have, like being able to sense the emotions of humans from a great distance. Also, there could be a plot where Bella has to hide her new vampire self from her human family and friends, which creates a lot of tense and emotional moments as she tries to keep her double life a secret.
The vampire Authority could be antagonists. They might see Sookie as an abomination since she was a fae - human before being turned into a vampire. They could try to eliminate her to maintain the 'purity' of the vampire race according to their own rules.
The main characters are Edward, who is a vampire, and Bella, who is a human. Edward is often depicted as mysterious, brooding, and having a strong sense of protection towards Bella.
Definitely Edward and Bella. Edward, with his centuries - old charm and vampire powers, and Bella, the newly - turned vampire. They are the focus because the honeymoon is a special time for them to explore their relationship further in their new vampire forms. In the fanfiction, we get to see their characters develop more as they face new situations together during this honeymoon period.
The Volturi could be antagonists. In the Twilight universe, they are the powerful vampire coven that enforces vampire laws. They might see the baby as a threat to their power or a violation of their rules. They could try to eliminate the baby or control Bella, Edward, and their family.