For subject headings for fictitious characters, comic and cartoon characters, imaginary places, fictitious organizations, etc., follow the Library of Congress Subject Cataloging Manual guidelines H 1610 "Fictitious Characters". For more specific instructions on comic and cartoon characters see H 1430; for legendary characters see H 1795.
CCS policy varies from the LC policy of waiting for the third appearance of a character, by tracing the character after the first appearance if it looks likely to recur. Add the character subject heading retrospectively to other records already in the CCS database if the heading is established later.
650 0 Poirot, Hercule (Fictitious character)|vFiction