Difference Between Facetious and FictitiousFacetious is used to describe speech that is meant to be funny but that is usually regarded as annoying, silly, or not proper: “Her facetious remark certainly did not fit the situation.”
Fictitious means tot true or real: “The characters in the novel are all fictitious.”

The book reviewer made a facetious remark about the fictitiouscharacters in the short stories.