Born into a very rich, upper-class family, Xaxior was named after his great grandfather, who had been both a well-known Sith and politician. The youngest of four children, Xaxior also proved to be the most... difficult. Diagnosed with numerous mental health disorders as a small child, he grew up sheltered and hidden away from public, as his parents were concerned with how Xaxior's problems would effect their family's image.
Thus, he was tended to mostly by servants in his family's lavish estate. However, fate seemed to have different plans for him. On his fifteenth birthday, he was treated to a day out of the house with his parents, at a local zoo. His issues manifested themselves profoundly there, however, when he was allowed to make contact with one of the rarer animals at a petting area. The animal clawed him across the face, to which he responded by brutally snapping it's neck and wildly flailing at it's corpse until he was successfully pulled away. This would have been the end for Xaxior's public life, had it not been for his own force sensitivity also manifesting when he accidentally force pushed away one of the guards at the zoo who was attempting to restrain him.
A nearby Sith lord felt the disturbance put into place by Xaxior's first usage of the force, and proceeded to escort Xaxior and his parents back to their home, where he was invited in and told of Xaxior's mental health history.
To his parents, Xaxior was a disappointment and was bad for their family image, but to the Sith lord he had extreme potential to be a Sith warrior. Happily, the wealthy couple parted with their son as he was taken away to train as a Sith.
The Sith lord's name was Darth Melchius, who proceeded to train him, and in time came to care for Xaxior as a son of sorts. Feeling truly happy for the first time, Xaxior was now free of the bondage he had felt trapped within his former home, and had someone who genuinely cared for him.
Xaxior's training, however, was not as kind to him as his master was. It seemed to have the exact opposite effect that, say, proper medical help would have had. Taught to focus on his rapidly shifting emotions, he was also urged to embrace his mental instability. Indeed, at heart Xaxior was essentially good, and he was torn between two very different natures, a "good" heart and a "bad" mind.
Over the years, his mental health only degraded further, with violent outbursts causing him to kill more and more often, depressive bouts causing him to hurt himself, and a voice in his head becoming louder and louder with each passing day.
At twenty-four, he became a Lord himself. Falsely believing him to be able to take care of himself, Melchius arranged for Xaxior's parents to purchase him an apartment in Dromund Kaas, which he introduced Xaxior to, along with news that Melchius was to leave for some time on business in Hutt Space.
Left alone once more, he knew not what to do but wait...