I had some computer problems that caused delays. But I have resumed progress.
As far as their back story - She is Aruni' Ka, a former Dark Jedi turned Gray after she was sent to assassinate her sister. The resulting battle between them left its scars both physically and mentally, resulting in the loss of her left forearm and right leg. He is Maro Rusk, her pilot, companion, and more. He found her shortly after the battle and nursed her back to health. When he received the order to kill her, something snapped. The two now follow their own somewhat unhinged code of honor and vengeance.
Thanks! Technically, neither are Sith... She's an ex-Sith who, because of internal conflict and years of physical hardship, has broken from the Sith and started following her own moral compass. He is an ex-Stormtrooper who had been under her command, but later realized that his loyalty to her was more than just loyalty.