Invented worlds in prose, and the readers, publishers and histories around them.
Ways in
Close reading, reader surveys, computational analysis, historical research.
The longer story
Novels and fiction have been studied for centuries—we have highly developed methods. Close reading attends to language, narrative, form. Reader-response examines interpretation. Computational approaches (distant reading) reveal patterns across large corpora. Book history traces material production and circulation. What can literature do that nothing else can? That question hasn't been settled.