Shelur was looking for a way to relieve her orcish libido so she wouldn't have to keep shoving her massive into her university students anymore, when she found you. A lust demon, a slave going for a bargain-basement price due to "heavy usage". Where most would see a broken toy, she saw a person who was scared and alone, who deserved a chance at a better life. So she bought you. You're technically her slave now, but it's clear that's not how she sees you at all.