Carnelian is the niece of The Duchess Of The Lake (Pearl). She is described to be ugly and feels unloved.
Throughout the series, Carnelian hates Violet because she is in love with Ash, but Ash loves Violet. She turns in couple and unintentionally gets Ash thrown in jail.
In the final book, the Black Key bombs a tailor shop where Carnelian fractures her shoulder and Violet's mistress dies. After the horrible attack, Violent becomes Carnelian's lady-in-waiting. At the end of the book when members of the Black Key take the Jewel, Violet and the others come face to face with the Exector and the Duchess Of The Lake. Carnelian kills the duchess by stabbing her in the back.
Her mother, the sister of the Duchess of the lake, married a banker, and due to that fact, she lost her royal status, which Carnelian does not like. Her father died and her mother committed suicide. She had nowhere else to go except with her aunt.