Belial seemed amused. “Did you not also learn the meaning of my name? Beli ya’al in the original Aramaic—or is it Hebrew? It means ‘never to rise.’ I alone among the Princes of Hell cannot walk on Earth in my own form. I must possess a body in order to exist in your realm.”

“You possessed Ariadne,” James said. “In the sickroom.”

“Only for a moment,” Belial said bitterly. “When my spirit possesses a human body, it is like a bonfire burning within a fragile casing of paper. The body will be destroyed within hours. Lilith, Sammael, all the others—they can walk upon Earth, even in their own forms. Only I am thus restricted, for Heaven punishes us all according to its lights. I of all the princes loved human beings most, so I alone am separated from walking among them.” As he spoke, he gestured. His hands were as beautiful and ageless as the rest of him, with slim, long fingers. His nails were matte black. “And then there is you.”

The burning had intensified in James’s veins. He could feel fever-sweat trickling between his shoulder blades, dampening his hair. He did not dare look down at his arm.

“The only host body I can use,” said Belial, “is one of my own blood. I tried with your mother, but that clockwork angel she wore prevented me from getting near her. Even when it was gone, Ithuriel protected her. She is too poisoned with angel blood to make a home for me.” His lip curled. “But you. We could share your body, James. My presence would cure the Mandikhor venom in your veins. You would live, and the power you would have would be immense. For are you not my heir, my own flesh and blood?”

James shook his head. “The demon attacks, the sickness—you caused all of it because you need me to be willing.” The last piece of the puzzle fell into place. James’s whole body throbbed with pain. “This is why you wanted Belphegor to be blamed for what you’ve been trying to do. For all of this. You’ve been trying to get around the law that says you cannot rise. You were never trying to fool us, the Shadowhunters, about who my grandfather was. You were trying to fool the others like you.”

“Angels above and demons of the Pit,” said Belial, examining his black nails. “Indeed. I don’t deny that.”

“You need me to volunteer myself for possession. To allow you to become me.”

“Quite,” said Belial. He looked bored.

“You took my grandmother’s happiness from her. You took my cousin Barbara’s life. And you want me to—”

“To give me your body for my rising,” said Belial impatiently. “Yes, yes. Because I can make it all stop. My creature on the bridge told you as much.”