Cordelia is the eldest daughter of Queen Umbra, and the sister of Nox. She becomes Aurora's step-sister after Umbra marries her father. While living at Lemuria's palace, she is said to be kind and compassionate, specially towards Aurora.
 Appearance and Personality
As her eldest daughter, Cordelia inherited most traits of Queen Umbra. She has long, jet-black hair that goes down to her hips and pallid skin, which she covers up with dark make-up. She sports a long black dress, and a similarly colored collar. She has a skinny build.
While living on the Lemurian Castle, Cordelia was shown to be kind and compassionate, specially towards her sisters. After Aurora's presumed death and Queen Umbra's coup d'état against the Lemurian empire, Cordelia reveals that her former nature was an act. In reality, she hated Aurora, and considered every day she had to put up with her as torture. Her true personality is, in fact, cruel and sadistic.
Despite being older than Nox, she is not as bright or strong as her sister. She is shown to be loyal to Umbra, and is willing to attack those who oppose her mother.
Cordelia is first seen along Queen Umbra, Óengus and Nox after the latter successfully separated Aurora from her comrades and brought her to the Forgotten Tower where she would be imprisoned and tortured. She is later seen outside the tower, guarding the moon, after Aurora manages to free her comrades from their prison. She reveals to Aurora that she was posing as a loving sister while living with her and her father, and that she truly despised Aurora's laugh and mannerisms, before attacking her as Crepusculum.
Cordelia is Umbra's daughter. She shares her mother's sadism and is more than willing to further Umbra's goals of conquering Lemuria.
Cordelia is Nox's sister. Their relationship is not explored in depth, but it is implied they were in good terms with each other and that they both worked together to further Umbra's agenda.
Cordelia became Aurora's step-sister after Umbra married Aurora's father. At first, she pretends to like Aurora and care for her. Unbeknownst of Aurora, though, Cordelia in reality despised the child's sole existence, and was hard for her to maintain her act up as she hated every facet of her personality.
Main article: Crepusculum
Cordelia transforms into a black serpent dragon in order to fight Aurora and her comrades alongside a pair of Black Shadows. During battle, she shows her brutish personality, resorting to heavy blows and threatening roars in order to deal damage to Aurora's party. As Crepusculum, she is resistant to magic and can physically decimate Aurora's party, but she is highly susceptible to physical blows and rarely uses non-damaging moves outside of her interruption counter.