Xiaan Amersu was a young, Twi'lek Jedi Padawan during the time of the Old Republic. Apprenticed to Anx Jedi Knight, J'Mikel, the two joined Skrilling Jedi Master Peerce, as they tracked the bounty hunter Aurra Sing through the under-levels of Coruscant. Some time earlier, Aurra Sing had come to Coruscant with the intention of murdering as many Jedi Knights as possible. Known for hunting Jedi, Aurra Sing was a former Jedi apprentice herself. Years of misfortune had transformed her into a wretched Dark-Sided force who blamed the Jedi for all of her ills. She took every opportunity to exact her revenge on those she viewed as her transgressors and had no hesitations for murdering Jedi.
As they followed Aurra's trail, Xiaan, J'Mikel, and Peerce came upon a squad of murdered Republic peacekeepers, no doubt Aurra Sing's work. Jedi Master Peerce continued to follow the trail while Xiaan and her master searched the surrounding areas for clues. When the pair caught up with Master Peerce, they found him slain having fallen victim to Sing's blade. Springing from the shadows, Xiaan watched as the Darksider engaged her master in battle.
J'Mikel fought bravely, but in the end Sing proved to be victorious. At such a young age Xiaan was forced to witness the murder of her master. Although Sing had a deep rooted hatred for the Jedi Knights, she spared Xiaan's life. The fact that Sing was not prepared to murder a child does not grant her any redemption. Sing informed Xiaan that the only reason her life was spared was so that she could grow up to become a full Jedi Knight, at which point Aurra would come back for her and a sweeter victory. The incident no doubt left Xiaan in a state of shock from which she recovered only after month's of care by the Jedi Temple's physicians.