Some fanfictions center around the idea of sacrifice. Edward might be sacrificing some of his own vampire - related hesitations for Bella's sake. It could also be about Bella sacrificing her human fears and inhibitions. Additionally, the theme of unity is present. Their first time is seen as a moment of true unity between them, two different beings coming together. This can be symbolized in different ways in the fanfiction, like through the way they hold each other or the words they exchange.
One popular Bella and Edward first time fanfic might be those that focus on their emotional connection deepening. For example, some fanfics might describe their first time as a very tender and loving moment, with a lot of dialogue about their feelings for each other. They might be in a secluded, beautiful place like a forest clearing. Another type could be where it's a more unexpected first time, perhaps during a moment of danger or high emotion when they realize how much they truly need each other.
Some fanfictions might focus on the 'what ifs' in their relationship. What if Edward didn't come back in New Moon? How would Bella's life change? This kind of theme adds a lot of drama and speculation. There are also themes related to the power dynamics between them. Edward has superhuman strength and abilities, while Bella is a human (at least initially). How does this affect their relationship? Is it a source of conflict or a way for them to protect each other?
One popular theme is the exploration of their relationship in different time periods or alternate universes. For example, some fanfictions might imagine them in a modern world with different social norms.
Some of the themes include the transformation of their characters. In a mob fanfiction, Bella might become a stronger, more assertive character having to deal with the mob environment. Edward, on the other hand, may struggle with his dual identity - his love for Bella and his loyalty to the mob. There's also the theme of family, but in a very different sense. Instead of the normal family unit, it's the mob family which has its own set of rules and hierarchies that they have to navigate around while maintaining their relationship.
One popular theme is the challenges they face as new parents. For example, dealing with the baby's special abilities that might be inherited from their vampire - human union. Another theme could be the reactions of their families to the new baby. The Cullens might be excited but also worried about protecting the baby from the outside world.
For Edward, there's likely a mix of relief and fear. Relief because he's finally expressing his deep love for Bella, but fear because he's exposing his true feelings and also worried about how this will change things. For Bella, she's probably mostly filled with excitement and a bit of shock. The excitement of this new level of intimacy with Edward, and the shock that this moment she might have dreamed of is actually happening.
One common theme is the family dynamic. Carlisle being the patriarch, his influence on Edward and Bella's relationship within the family framework is often explored. For example, in many fanfictions, he helps them navigate the difficulties of being part of a vampire family.
Some fanfictions might focus on alternative universes. In these stories, Edward and Bella could be in a completely different setting, such as a modern - day city without the presence of vampires and werewolves. But their love still manages to develop in unique ways, which is really interesting for fans who want to see a different take on their relationship.
Some popular themes include their relationship development, like how they deal with the challenges of being in a relationship between a vampire and a human. Another theme could be their adventures together, facing various supernatural threats in the 'Twilight' universe.
One common theme is the element of mystery. Edward is often portrayed as this mysterious figure, and when they first meet, Bella is immediately drawn to that mystery. For example, in many fanfictions, Edward has an air of secrecy about him that makes Bella curious.