Princess Jaehaera Targaryen was the daughter of Aegon II Targaryen and his sister-wife and Queen Helaena Targaryen, and the first wife and queen of her cousin Aegon III Targaryen. Jaehaera had a twin brother Jaehaerys Targaryen and a younger brother Maelor Targaryen. The dragon Morghul was bound to Jaehaera.
She was small of stature. Jaehaera is described as a sweet simple girl of six at the time of her brother's murder. As a babe, she showed no emotion.
After the death of Prince Lucerys Velaryon, Prince Daemon Targaryen declared vengeance, writing that there would be “an eye for an eye, a son for a son”.
Princess Jaehaera was present in the Tower of the Hand when Blood slew her twin Prince Jaehaerys. Prior to the boy's death, as the queen prevaricated, Cheese warned her to make a choice soon, before Blood grew bored and raped Jaehaera.
When the queen’s dragons first appeared in the skies above King's Landing, Lord Larys Strong spirited Jaehaera out of the city along with her father and younger brother Maelor. Lord Larys led them out through a secret passage of Maegor's Holdfast, of which only he had knowledge. Jaehaera was put in the charge of Ser Willis Fell, who swore to bring her safely to Storm's End.
Following the deaths of her parents, brothers, and uncles in the Dance and the victory of the Blacks, Jaehaera was married to King Aegon III as part of the peace agreement.
Two years after her marriage, Jaehaera died when she was impaled on the spikes of the dry moat of Maegor's Holdfast. She lived for a half hour in agony before her death, which ended the line of the marriage of King Viserys I and his second wife Alicent Hightower.
Jaehaera's death was officially deemed a suicide, akin to that of her mother Queen Helaena. However, many suspected that she had in fact been murdered at the instigation of Lord Unwin Peake, the Hand of the King and one of the seven regents, as Lord Peake hoped to marry his own daughter to King Aegon instead. It was variously suggested that Jaehaera had been murdered by Ser Mervyn Flowers of the Kingsguard, bastard brother of Lord Peake, who had been at her door when she died; or that Ser Mervyn had merely stood aside to allow Tessario the Tiger, a sellsword in Lord Peake's service, to do the deed.