Lori is half drow. Her mother to spite her brother, who has always desired her, lay with a slave human. In a fit of rage, the brother killed his sister (Lori's mother) and in disgust handed her over to the assassins guild for game, with the thought she would perish under great duress.  
But the guild thought otherwise and began training her, not for her benefit but because her cross parentage gave them an option not normally available in an operative. There she grew up, tormented by her peers. Though the Drow found uses for her, their hated of her were ever present and were she to quit or die would simply laugh at the half-breed's failure. Her uncle a mage of incredible power, particularly despised her for her mother's 'sin', it was he who gave her the single scar to show his dominance and to this day plagues her still. Only her aunt showed her any kindness, but her aunts dedication to Lolth was absolute and behind that kindness lay madness. Thus Lori's youth was alone with one focus, survive it all. And that she did, in fact she tended to out shine all, which only gave them reason to hate her more.  Thus it was when the chance came for an assignment to go above, she took it with the secret hope that somewhere above she would find what did not exist below.