Another theme is the idea of found family. The Cullens in Twilight are a family unit, and the Lost Boys also have their own tight - knit group. Fanfictions might bring these two groups together and explore how they interact as families. They could share their different ways of living as vampires and how they protect their own. It's a theme that often leads to some heartwarming and also some tense moments in the stories.
One common theme is the struggle between good and evil in the context of vampirism. In both Twilight and the Lost Boys, vampires are central, and fanfictions often explore whether a vampire can truly be good or if they are always doomed to be a creature of the night. For example, in some fanfictions, a character from Twilight might interact with a Lost Boy and question their own moral code regarding blood - drinking.