The theme of the battle between good and evil also appears. Since Harry has always been associated with fighting against dark forces in the wizarding world, when he becomes a vampire, he may face new forms of evil. Bella, having been involved in the vampire - related conflicts in her own story, joins him. Fanfictions might show them using their combined powers and knowledge to fight against a greater evil that threatens both the wizarding and vampire worlds, like a powerful dark wizard who wants to use vampire powers for his own nefarious purposes.
Love and relationships are also big themes. The idea of a relationship between Harry and Bella is quite unique. They come from different fictional universes, so the fanfictions often explore how they can overcome their differences to be together. It's not just about romantic love but also friendship and loyalty. They might have to face opposition from their respective friends and families. For instance, Hermione might be worried about Harry's new vampire state and how it could affect him, while the Cullens could be hesitant about Bella's relationship with Harry.
One common theme is the exploration of power. Harry already has his wizard powers, and when he becomes a vampire, he has to deal with a whole new set of powers. Bella, on the other hand, has her own allure in the vampire world. Another theme is identity. Harry has to re - define himself as a vampire - wizard hybrid, and Bella has to figure out how she fits into this new world with Harry. For example, in some fanfictions, they struggle with how the wizarding community will accept a vampire Harry and how Bella's vampire friends will react to her relationship with a wizard - vampire.