Another challenge is the physical and emotional transformation Bella goes through. When she decides to become a vampire to be with Edward forever, she has to endure the pain of the transformation. And emotionally, she has to give up her normal human life, like going to college in a traditional way, and deal with the changes in her relationships with her human loved ones. It's a complex and difficult process for both of them.
One challenge could be financial. Raising a baby is expensive. Another might be dealing with family opinions on how to raise the child. And there's also the physical exhaustion from taking care of a baby.
One challenge could be trust. Since she has a child, Bella might be more guarded. She needs to be sure that Edward is not just passing through but is truly committed. Another challenge is time management. With a child, she has a lot of responsibilities, and finding time for a relationship with Edward might be tough.
One challenge could be dealing with the vampire - human dynamic. Since Bella is now a vampire too, they have to ensure the baby is safe from any vampire - related threats. Also, they might face scrutiny from the vampire community as their lifestyle is not exactly normal for raising a child.
In the fanfiction, Carlisle's sense of duty to his family and the vampire code might be a hurdle. He has to balance his feelings for Bella with his responsibilities to the Cullen family. Also, Bella's own human life and her relationships with other humans, like her father, could be a complication. How can she maintain those relationships while being in love with Carlisle? There's also the issue of secrecy. Their relationship has to be kept hidden from the outside world to protect both of them.
In the Bella - Edward love story, Bella is a new student in Forks. Edward, a vampire, is immediately intrigued by her scent which is very alluring to him as a vampire, yet he also wants to protect her. They start to get to know each other and fall in love. However, this love isn't without problems. There are other vampires who don't like the idea of a human being so close to their kind. Edward's family also has concerns. But Bella and Edward's love is strong. They go through many adventures together, from dealing with vampire rivals to Bella making the decision to become a vampire herself to be with Edward forever.
One big challenge is secrecy itself. They have to hide their relationship from their friends and family. For example, Bella can't tell her human friends about her relationship with a vampire. Another challenge is the danger that Edward's vampire nature brings to Bella. Other vampires might target her to get to Edward.
The key moments are quite a few. Firstly, when Bella and Edward meet for the first time, there is an instant connection. Then, when Edward reveals his vampire identity to Bella, it's a turning point. After that, their trips and adventures together, like going to the meadow, are important. Also, the times when they face danger together, for example, when they deal with the Volturi, strengthen their bond. And the moment when Bella decides to become a vampire for Edward is a crucial part of their love story.
Bella herself might struggle with her identity. She has been so caught up in the vampire world before, and now being with Jacob, a werewolf, she has to redefine who she is and where she belongs. She may also worry about how her human family and friends will react to her being with a werewolf.
One challenge could be communication. Since Bella is a mermaid and Will is a human, they might have different ways of expressing themselves. For example, mermaid language and signs might be difficult for Will to understand at first. Another challenge could be dealing with the different laws and rules of their two worlds. Mermaid society might have rules about interacting with humans that Bella has to navigate while Will might face problems in his human world if he is seen spending too much time with a'mysterious girl' like Bella.
One challenge could be self - doubt. She might think she is not worthy of love because of the scar, which can prevent her from fully opening up to potential partners. For example, she may reject someone's advances before they even get to know her better.