Well, without reading it specifically, it could be about a half - lost or half - forgotten aspect within the Twilight universe. Maybe it focuses on a character who has lost half of their identity or power in the context of the Twilight story.
One common theme is the clash of different vampire cultures. In 'The Lost Boys', they are more wild and rebellious, while in 'Twilight' the Cullens are more refined. Fanfictions often explore how these two types interact.
One interesting 'lost in twilight fanfiction' could be the ones that explore alternate endings. For example, a story where Bella makes a different choice regarding her relationships. It adds a fresh perspective to the Twilight universe.
One main theme is the clash of vampire cultures. The Twilight vampires are often more civilized and secretive, while the Lost Boys are wild and rebellious. Another theme is the idea of belonging. Characters from one universe may struggle to fit into the other. For example, a Twilight vampire might find the Lost Boys' way of life too chaotic.
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.
One main theme is the clash of different vampire cultures. Twilight has its more civilized, 'vegetarian' vampires, while Lost Boys are wilder. Another theme is the idea of forbidden love, which is common in both universes. It could be between a character from one and a vampire from the other.