Taming demons for beginners

"Rule one: Don't look at the demon. When I arrived at my uncle's house, I expected my relatives to be like me--outcast sorcerers who don't practice magic. I was right about the sorcery, but wrong about everything else. Rule two: Don't listen to the demon. My uncle chose a far deadlier power. He calls creatures of darkness into our world, binds them into service contracts, and sells them to the highest bidder. And I'm supposed to act like I don't...