The mother of Tenebrae, who would later rise to become the Sith Emperor, was a female Sith working as a farmer. She was also the wife of Tenebrae's father.
In the year 5107 BBY, her son, Tenebrae, realized his potential as being Force-sensitive. Her husband challenged her about Tenebrae's power, and she confessed to having had an affair with the ruling Sith Lord. Consumed by anger, her husband assaulted her, but her son intervened, using only his mind to snap the neck of his "father". As retribution for her infidelity and betrayal of the family, Tenebrae used the Force to torture her for months, ultimately killing her while simultaneously improving his Force abilities.
Dramath brought her up again when he told Tenebrae that she should have followed his instructions to kill her son by drowning him. Tenebrae responded that he had ended his mother's suffering a long time ago.
The first mention of Tenebrae's mother occurred in The Old Republic: Revan, a novel written by Drew Karpyshyn and published on November 15, 2011.