Tenebrae was born in the decades before the Great Hyperspace War on Medriaas, a fertile and vibrant agricultural world on the far fringes of the Old Sith Empire. He was born to a family of simple farmers, and it was said that he was born with eyes as black as the void of space. He never cried, even as a infant, no animal would come near him, and when he spoke, his voice carried a power and weight that a child should not have. When he was six years old, he began manifesting signs of being strong in the Force, however, his parents were not Force sensitive, and as a result, his father was suspicious. He confronted his wife, who admitted to having cheated on him with the Sith Lord who ruled the planet. The farmer became enraged over his wife's adultery, attacking her. Tenebrae fed on the father's anger and hate to call upon the dark side, and telekinetically broke his neck with a mere thought. He then tortured his mother for months with the Force for having betrayed their family, eventually killing her. Afterwards, he forced the other villagers to bow down to him, torturing and killing those who refused with the Force. For the next few years, his influence and reputation spread throughout the neighboring villages, and he raised legions of followers, some frightened into obedience, and some fanatically devoted to him. He slaughtered thousands in his rise to power, with many of them tortured for days in public executions to feed his insatiable appetite for suffering, savoring their agonies.
Tenebrae's birth father, Lord Dramath, had heard rumors of his illegitimate son's activities, but they happened in a remote and unimportant area. He had long forgot about the farm woman who bore him a son, and he thought what was happening in a few small villages didn't concern him. He didn't decide to go see Tenebrae until four years had passed. He had gone to to decide if Tenebrae would be suitable to serve Dramath, or if he should be killed; however, Tenebrae did not want to die or merely serve. When they met, Tenebrae proved the stronger of the two. Even though he was only ten years old, he stripped his father of his power and his mind, with Lord Dramath's last moments weeping in terror, looking up into his son's black eyes. It took Tenebrae three more years to subjugate the rest of Medriaas. While Dramath's firstborn son fled Medriaas, other Sith Lords tried to seize the unoccupied throne of the world, only to fall before Tenebrae, who became more ruthless and powerful with each victory.
When he was thirteen, he came before Marka Ragnos, the Dark Lord of the Sith and the ruler of the Sith Council and Sith Empire. Lord Ragnos was impressed by the youth's power and ambition, and recognized him as the ruler of Medriaas, bestowing on him the name of Lord Vitiate. Lord Vitiate returned to his home world, which he renamed Nathema, and proceeded to rule and study the Dark Side. He built a palace on the site of his childhood home, where he killed his parents. His rule lasted for a hundred years.
- The Old Republic: Revan (First appearance)