Gideon is the protagonist of Gideon the Ninth. She is 18 years old, openly lesbian, and an indentured servant to the Ninth House. The third-person limited narrator follows her perspective for the whole novel. Gideon is a prodigy with the sword and knows very little about the world due to her isolation in the Ninth. Gideon is irreverent and looks for opportunities to crack jokes; this is often a defense mechanism against her hopeless circumstances. Gideon’s mysterious origins of falling into the Ninth House as an infant with her dead mother allow Muir to explore Gideon’s character in subsequent novels, despite her death at the end of Gideon the Ninth and allow Gideon to remain a relevant character after her primary narrative has ended.

Gideon carries a crushing amount of guilt over the death of Harrow’s parents. She tattled on Harrow as a child, hoping to gain the approval that Priamhark and Pelleamena never gave her, and instead they killed themselves. Harrow uses Gideon as her “whipping girl” to express her own self-loathing (330). Gideon incorrectly interprets this as an expression of Harrow’s hatred of Gideon, which affirms Gideon’s own self-loathing.