One key concept is the idea of the implied author. The implied author is not the real author but the one created through the text. It's a sort of presence that guides the reader's understanding of the story. Another important aspect is the use of point of view. Different points of view can greatly influence how the reader perceives the characters and events in the fiction.
In 'The Rhetoric of Fiction', Booth emphasizes the role of rhetoric in fictional works. Rhetoric here means how the author uses language to persuade the reader. For example, the author might use certain words or sentence structures to make the reader sympathize with a character. Also, the concept of the unreliable narrator is significant. An unreliable narrator can add complexity and intrigue to the story as the reader has to question the truthfulness of what is being told.