Ser Jorah Mormont is the son of Lord Commander Jeor "Old Bear" Mormont. Ser Jorah became Lord of Bear Island in his own right when his father joined the Night's Watch. He earned his knighthood during Greyjoy's Rebellion for being one of the first of the royalist forces through the walls of Pyke. Ser Jorah was attainted and exiled from Westeros for selling men caught poaching on his land to slavery in order to support his former wife's lavish lifestyle.

Jorah found Daenerys Targaryen and swore his sword to Viserys Targaryen shortly before her marriage to Khal Drogo. He was originally a spy for Robert Baratheon in the hopes of buying back his knighthood, but after Robert died and Ser Jorah got to know Dany, he fell in love with her and attempted only to help her. In A Storm of Swords, Daenerys discovers what his true prupose was and commands him and Ser Barristan Selmy to crawl through sewers on a near-impossible mission to help her conquer Mereen. Afterwards, Dany forgives Selmy, but banishes Jorah when he reveals that he betrayed her because of a promise from Varys the Spider that Jorah could earn a pardon. Dany considers him to be the "once for love" part of her prophecy, though this is not entirely certain.