Ashara was tall, with long dark hair and haunting violet eyes. She had a reputation for great beauty. Many men were infatuated with her, including Barristan Selmy and, according to rumor, Eddard Stark.
Ashara was a lady-in-waiting to Princess Elia Martell. She was present at the Tourney at Harrenhal, where she danced with several men, including Eddard Stark after his brother Brandon spoke with her. 
After the events of the Tower of Joy, Ned Stark went to Starfall to inform House Dayne of Ser Arthur's death and return to them his greatsword, Dawn. Ashara jumped from the top of one of the towers of Starfall, called the Palestone Sword, on the cliff atop the sea. Her body was never recovered. After these events, Ned Stark returned to Winterfell with the infant Jon Snow, whom he claimed as his bastard son, refusing to name the child's mother. This sparked rumors that Ashara had been the mother of Stark's bastard, and that grief at learning that her lover had been responsible for her brother's death was the cause of her suicide.
Ser Barristan Selmy believes that Ashara gave birth to a stillborn daughter. According to Selmy, a man dishonored her at Harrenhal during the tourney and got her with child. In Selmy's account, it was grief at the death of her child (and possibly of her brother's death) and shame at being dishonored that led to Ashara's suicide. Also, Selmy thinks that he could have prevented Ashara's suicide if she had known of his feelings for her; that he thinks would have led her to seek his aid instead of a Stark's aid.