Grace Poole is a “hard-favored and matronly” alcoholic in her thirties who is employed by Mr. Rochester to look after Bertha Mason. Grace Poole is further useful to Mr. Rochester and the rest of his staff because they are able to blame every strange occurrence in Thornfield Hall on Grace. The laughter that Jane hears through the walls, the fire in Mr. Rochester’s room, the attack on Mr. Mason, and the sinister figure in Jane’s room are all attributed to Grace’s eccentricities. Of course, everyone besides Jane knows these incidents were carried out by Bertha Mason, but Grace provides a useful scapegoat to keep Jane successfully in the dark. Grace is essential to the novel’s unfolding plot because she acts as a red herring—a clue or piece of information in mystery fiction that is, or is intended to be, misleading—which conceals the truth from Jane, and subsequently the reader, until the big reveal in Chapter 26. 

Grace’s character contributes to the mysterious and foreboding tone that persists throughout the novel. Jane is baffled by Grace’s purpose at Thornfield and does not understand why she is not dismissed or suspected of having malicious intentions. Overtime, Jane becomes aware that the rest of the staff knows something about Grace that she is not privy to. For example, she catches two other servants whispering about Grace, but they stop speaking the moment that they see Jane because she “does not know” what they are gossiping about. This baffling interaction causes Jane to conclude that “there was a mystery at Thornfield; and that from participation in that mystery I was purposely excluded.” Overtime, Jane becomes slightly obsessed with Grace, whom she refers to as a “living enigma,” and she comes to outlandish conclusions. For instance, she entertains the ideas that Grace is a murderer and/or Mr. Rochester’s lover. An eerie and mysterious tone is an essential component to any Gothic novel, and Grace’s ambiguous purpose helps foster Jane’s paranoia until the real source is finally revealed.