In this interdisciplinary study, we explore the understudied effects of growing cultural entrenchment on the form of stories with a long reproduction history. Drawing on insight from literary theory, theoretical linguistics, and cultural evolution theory, we argue that changes in the cultural entrenchment of fairy tales and folk stories are reflected in (small) structural ‘mutations’ in the story. More specifically, we aim to show that with the increasing familiarity of “Little Red Riding Hood”, its story frame and characters have gradually become part of the author and audience’s shared world knowledge, which is encoded in the type of linguistic devices used to introduce the characters. To this end, we performed a Bayesian logistic regression analysis on a diachronic collection (late 18th century–2015) of the world’s most iconic fairy tale, using automatically generated time estimations for a subset of undated reproductions in the story lineage, and including these estimates and approximated measurement errors in the statistical model. Results show that there is indeed a marked increase of linguistic markers that indicate that the characters are already known or “accessible” to the audience. This development reflects the author’s changing intuitions and beliefs about the familiarity of the story, and, indirectly, the changing expectations of the story’s audience regarding the appearance of certain characters in the story frame. Notably, this study is the first to quantitatively describe the diachronic development of a story (and the concepts associated with it) into the realm of ‘shared knowledge’, showing that it is a slow and gradual process. The results help refine our understanding of cultural evolution as well as the workings of speaker-addressee dynamics. Conceptualising the observed linguistic mutations as an instance of guided variation, we argue that the increase of definite first mentions as a function of cultural entrenchment can be treated as an example of variation guided by pragmatic principles such as Grice’s Maxim of Quantity, making character introductions as informative as (and not more informative than) required.