Second daughter of King Aegon III Targaryen and his queen Daenaera Velaryon, born in the Red Keep in 147 AC. Rhaena grew up in the shadow of an older sister already famous for her wildness, Daena the Defiant, and a younger sister already famous for her brilliance, Elaena; of the three princesses she was the pious one, given as a child to long hours in the royal sept and to the company of the septas of the Red Keep. When her father died in 157 AC and her brother Daeron took the throne she was still a girl of ten, and when Daeron in his turn fell in Dorne and the second brother Baelor was crowned, her life and the lives of her sisters changed in a single decree.
Baelor I, the Blessed and the Beggar King, would not abide the presence of women near him at court, and least of all the presence of his own sisters whose beauty he confessed tempted him to sin. In 161 AC he ordered Daena, Rhaena, and Elaena confined to a windowless suite of apartments behind the throne room, a building thereafter called the Maidenvault, where the three of them lived for the remaining ten years of his reign. Daena raged against it and slipped out twice; Elaena bore it like a sentence and read her way through every book the king would send in to her; Rhaena, alone of the three, met it with the answer her brother had hoped: she took her vows in the Maidenvault and became a septa of the Faith.
After Baelor's death in 171 AC the doors of the Maidenvault were opened, and the three sisters were free; but Rhaena had been a septa for a decade by then and had no other life to return to. She passed the rest of her days in the Great Sept of Baelor, the chief of its septas in all but title, attending the king's family at births and funerals and councils, and was reckoned by her nephew Daeron II to be the most learned woman of the dynasty. She died in 191 AC of a wasting illness, having lived through the reigns of four kings, and was buried beneath the floor of the Sept she had served almost the whole of her adult life.