Rhaego is the name of Daenerys and Khal Drogo’s unborn son. The name comes from Daenerys’s brother Rhaegar. To save Khal Drogo, Daenerys agrees to let Mirri perform a spell in which a death will be traded for Khal Drogo’s life. Later, Daenerys learns that she traded Rhaego’s life for Khal Drogo’s.