Demon Thief By Darren Shan

(Demonata # 2)
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Kernel Fleck has always known he's weird. He sees lights. Strange, multi-colored patches of light, swirling through the air. But it's not until a window opens into a demon world, with horrific consequences, that Kernel discovers his powers. As a Disciple, his mission is to hunt vicious, powerful demons to the death...