Princess Rhalla Targaryen was the daughter of Prince Aegon and Princess Rhaena Targaryen. She had a twin sister, Aerea. Rhalla's parents were married in 41 AC. As this was an incestous marriage, this act led to a rebellion of the Faith. When Rhalla's grandfather, King Aenys I Targaryen died, it was not Rhalla's father, Aenys' eldest son and heir, Prince Aegon who was crowned king, but her great-uncle (and later step-father), Prince Maegor. It is unknown what happened to Princess Rhalla later in life.