Half-Demon/Shannara

descendants of a sect called Armageddon's Children, people who are part-Man and part-demon and who are therefore susceptible to being corrupted and controlled by dark forces.
Eretria and her mother were constantly hunted by those who sensed their magic, and her mother was ultimately killed by a demon who sought Eretria. Before her mother died, she gave Eretria to Cogline to raise, who promised to keep Eretria safe after her mother convinced him that Eretria was just as able to be a force for good as she was for evil. Cogline was Eretria's guardian until she was somehow separated from him and sold to her first owner.