She is one of the central figures in the Middle Irish text Finn and Gráinne, as well as the 17th-century tale The Pursuit of Diarmuid and Gráinne, which tells of her betrothal to Fionn mac Cumhaill, leader of the Fianna, and her subsequent elopement with Fionn's warrior Diarmuid Ua Duibhne.
Eventually, Fionn pardons Diarmuid after Aengus intercedes on their behalf; the pair settle in Kerry and produce five children.
Years later Diarmuid is wounded by a boar while hunting with Fionn, who stalls in healing him until it is too late; texts vary on Gráinne's subsequent actions.
He was elderly when [the High King] Cormac Mac Art gave his daughter Gráinne to him in marriage.
The Pursuit of Diarmuid and Gráinne shares a number of similarities with the story of Tristan and Iseult, and to a certain extent the love affair of Lancelot and Guinevere.