The possessiveness of Bella and Rosalie can cause a great deal of unrest within the Cullen family. For instance, if Rosalie is possessive of her vampire 'ideals' and Bella starts to oppose them, it can create a divide. The family might have to take sides, which could lead to internal conflicts.
If Rosalie becomes overly possessive of Bella's relationship with Edward, it could potentially lead to family members having to mediate. Carlisle, for example, might try to step in to smooth things over, but it could be difficult as both Rosalie and Bella are strong - willed, and this possessiveness can put a strain on the family's unity.
Well, it shakes things up quite a bit. For one, Edward's relationship with Bella changes in a new way. They are now on more equal footing as vampires. The family has to adjust to having a new vampire in the house. Carlisle, as the head of the family, has new responsibilities towards Bella. He has to guide her in the vampire ways.
The Cullen family would likely support Rosalie in various ways. Carlisle, with his medical knowledge, would be constantly monitoring her health and that of the baby. Esme would probably be there to offer emotional support, being like a mother figure to Rosalie. The others, like Emmett, Rosalie's partner, would be her physical protectors.
Often, Jasper's possessiveness shows as him being constantly by Bella's side. He might glare at anyone who gets too close to her.
One idea could be that Bella discovers Rosalie's possessive nature towards her new vampire life. Rosalie might try to control Bella's actions to prevent her from making what she sees as mistakes. For example, Rosalie could be possessive over the 'right' way to be a vampire and try to keep Bella from straying from it.
In Rosalie and Bella mates fanfiction, Rosalie's character development could involve her letting go of her past traumas more easily with Bella's presence. She becomes more forgiving and less bitter. Bella's development could be quite complex. She might grow to have a more nuanced view of the vampire world. She could start to question some of the things she once took for granted. Their relationship forces them both to look at themselves and grow in ways they hadn't expected.
It can lead to Bella having to re - evaluate her place in the vampire world. If Rosalie, who is an important part of the Cullen family, rejects her, it might make Bella more determined to prove herself or it could make her feel more isolated. This could then cause her to seek other allies or make different choices in her relationship with Edward.
The Cullen family dynamics would change significantly. Carlisle, as the head of the family and a doctor, would be deeply involved in monitoring Alice's pregnancy. Esme would be motherly, providing emotional support. Rosalie, who has her own complex feelings about motherhood, might have a mixed reaction. She could be jealous in a way, but also protective. This would create new tensions and bonds within the family.
Their personalities interact in various ways. Rosalie, being proud and protective, might initially be overbearing towards Bella. However, as time passes, she realizes that Bella has her own strength. Bella, being gentle and curious, might be intrigued by Rosalie's confidence. She may start to imitate some of Rosalie's behavior in a positive way. Also, their different approaches to relationships, with Rosalie being more guarded and Bella more open - hearted, can lead to interesting conversations and developments in the fanfiction.
It can create a lot of tension. For example, if Harry has other friends or potential love interests, Fleur's possessiveness might lead to jealousy and arguments. This can drive a wedge between Harry and his friends or make the relationship with the other love interest more complicated.
Luke's possessiveness can change the alliances in the fanfiction. Other characters might side with Percy against Luke, or some might be influenced by Luke's possessive behavior and turn against Percy. This reshapes the power dynamics in the story.