Claudia first mentions her mother as a woman named Cardi, and that she left her father, a former Roman Centurian, after Claudia was born. Cardea had never told Claudia's father that she was a goddess, so Claudia was not informed of that fact by her father. That led to Claudia believing that she was just a legacy of Mercury.
During the Misfortunes at Camp Jupiter, with Mercury's assistance, Cardea sent clues to her daughter, helping her save all of New Rome. Due to Claudia's achievement, which included saving most of the minor gods and goddesses from fading away, she was permitted to briefly contact her.When Cardea reveals herself to Claudia and tells her that she is her mother. She thanks Claudia and gives her daughter her tattoos before leaving.
Cardea has dark hair, dark eyes, and a broad nose. She strongly resembles Claudia.
Cardea is shown to be a caring goddess who, while not addressing her daughter directly, is often around. She is shown to deeply resent how the gods are not allowed to be involved in their children's lives. When asked why she could not help more during the crisis in New Rome, her faced clouded over, and answered "Because reasons."