Dio is Eo's younger sister and Kieran's wife. Based on Darrow's account, she is stunningly beautiful and almost the exact lookalike of Eo. In Red Rising, her sister Eo told her of her pregnancy. Later, Darrow is reunited with his family in Morning Star and sees Dio again, almost thinking her to be Eo. She and Kieran are married after both their spouses had passed on, though they have a happy relationship and are expecting a child together.
- Dio means God in Italian.