B'Etor was one of the Duras sisters who were responsible for the start of the Klingon Civil War. She was the younger sister, the more seductive (and more promiscuous) of the two. She and Lursa supported their nephew Toral as the new Chancellor of the Klingon High Council. Toral was the illegitimate son of their brother Duras. She staked Toral's claim just as Jean-Luc Picard, who was the Arbiter of Succession, was about to pronounce Gowron as Chancellor. In determining their claim, Picard went planet-side and paid an invited visit to B'Etor and Lursa. B'Etor attempted to convince him that Toral's challenge must be approved. B'Etor made a futile effort to seduce Picard. (TNG: "Redemption")
When Picard designated Gowron as the rightful Chancellor, she and her sister took up arms against Gowron. They were supported by the Romulan Empire, who wished to see the alliance between the Federation and Klingon Empire fall apart. They kidnapped Worf and B'Etor took a liking to him and offered herself as a mate to him in exchange for his cooperation. He declined. B'Etor and her sister's plot failed due to a Federation blockade of Romulan ships, which denied them aid and supplies. It more importantly exposed their alliance with the Romulans who most Klingons hated. This caused B'Etor and her sister's support to erode. (TNG: "Redemption II")
The Duras sisters were also responsible for selling bilitrium to Bajoran Kohn-Ma terrorists in 2369. In order to raise capital to rebuild their forces, they offered the Bajoran Kohn-Ma terrorist Tahna Los bilitrium in return for gold-pressed latinum while plotting to sell him out to Elim Garak and the Cardassians once they were paid off. (DS9: "Past Prologue") Another capital-raising scheme had them seizing a Pakled magnesite mine on Kalla III, overseen by the Dopterian Gorta, and selling its explosive ore to an Yridian, Yog. B'Etor and her sister were also falsely accused of an attempted murder of the members of the Mogh family in 2370. (TNG: "Firstborn")
In 2371, the sisters worked with the El-Aurian scientist Tolian Soran and raided a Romulan outpost to acquire trilithium in exchange for Soran's trilithium bomb. In a recurring theme, she appeared interested in "initiating a mating ritual" with Soran. She was killed in orbit of Veridian III when her Bird-of-Prey fought against the USS Enterprise-D. (Star Trek Generations)