Jaehaera was the only daughter of Aegon II Targaryen and his sister-wife, Helaena Targaryen. She presumably had a very close relationship with her mother. After Lucerys Velaryon was killed by her uncle Aemond Targaryen, his step-father Daemon Targaryen hired two assassinates to kill Aegon's and Helaena's children. One was a former Goldcloak and the other was a rat-catcher who knew all the sewers around King's Landing. This meant that they both had perfect recognition of the layout of the Red Keep. After breaking into the royal apartments, they found Helaena putting her children to bed. They demanded a son for a son. Her mother pleaded that kill her instead, but they refused. She named Jaehaera's younger brother Maelor as the victim. However, Cheese just told Maelor that his mother wanted him dead, and some believe that Helaena named Maelor because Jaehaerys was heir to the Iron Throne, or because Maelor was just too young to understand. This request became an act of defiance against the Greens, as Blood just beheaded Jaehaerys with a single blow. By the time the guards had came, the Queen was cradling her son's body. Jaehaerys' death would eventually led to his mother's insanity and suicide. When the Dance of the Dragons was over, her father resumed his kingship by killing his half-sister, Rhaenyra Targaryen. He was poisoned half a year later, which meant that her cousin Aegon III Targaryen became the ruler of the Seven Kingdoms. At some point, Jaehaera married Aegon, declaring an official end to the civil war of House Targaryen.
In the books Edit
After the murder of Princess Rhaenyra's second son, Prince Lucerys Velaryon, Prince Daemon Targaryen declared vengeance, writing that there would be "an eye for an eye, a son for a son".
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 Rhaenyra Targaryen’s dragons first appeared in the skies above King's Landing, Lord Larys Strong spirited Jaehaera out of the city along with her father, Aegon II Targaryen, and younger brother, Maelor. 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 her cousin King Aegon III Targaryen as part of the peace agreement. Since she was eight years old at the time of the marriage and Aegon was eleven, it was not consummated.
Two years after her marriage, Jaehaera died when she reportedly threw herself from Maegor's Holdfast and was impaled on the spikes of the dry moat below. She lived for a half hour in agony before her death. With her ended the line of the marriage of King Viserys I Targaryen 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 been murdered at the instigation of LordUnwin 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 Mervyn had merely stood aside to allow Tessario the Tiger, a sellsword in Lord Peake's service, to do the deed.