Juliette and her sister Elinor reflected in a bedroom mirror. The lipstick colour that Elinor suggests for Juliette is “Heart Stopper 23”. On page 23 of Joy Fielding’s 2007 novel Heart Stopper (not the Alice Oseman book on which the Netflix series “Heartstopper” is based), this line appears: “…the natural pout of his lips was exaggerated by bright, Marilyn-Manson-red lipstick.”