Simon—Simon, who had been silent till that moment; Simon, who Clary had almost forgotten was there—stepped forward. “I am willing.”

Asmodeus’s eyebrows shot up. “What was that?”

Isabelle seemed to catch on before anyone else. She paled and said, “No, Simon, no!” but Simon went on, his back straight, his chin lifted.

“I also have an immortal life,” he said. “Magnus isn’t the only one. Take mine; take my immortality.”

“Ahhhh,” breathed Asmodeus, his eyes suddenly shining. “Azazel told me of you. A vampire is not interesting, but a Daylighter! You carry the power of the world’s sun in your veins. Sunlight and eternal life, that is a power indeed.”

“Yes,” Simon said. “If you’ll take my immortality instead of Magnus’s, then I give it to you. I am—”

“Simon!” Clary said, but it was already too late.

“I am willing,” he finished, and with a glance around at the rest of the group, he set his jaw, with a look that said, I’ve said it. It’s done.

“God, Simon, no,” said Magnus, in a voice of terrible sadness, and he closed his eyes.

“I’m only seventeen,” Simon said. “If he takes my immortality, I’ll live out my life—I won’t die here. I never wanted immortality, I never wanted to be a vampire, I never wanted any of it.”

“You won’t live out your life!” There were tears in Isabelle’s eyes. “If Asmodeus takes your immortality, then you’ll be a corpse, Simon. You’re undead.”

Asmodeus made a rude noise. “You’re a very stupid girl,” he said. “I am a Prince of Hell. I can break down the walls between worlds. I can build worlds and destroy them. You think I can’t reverse the transformation that Turns a human to a vampire? You think I can’t make his heart beat again? Child’s play.”

“But why would you do that?” Clary said, bewildered. “Why would you make it so that he lived? You’re a demon. You don’t care—”

“I don’t care. But I want,” said Asmodeus. “There is one more thing I want from you. One more item to sweeten the deal.” He grinned, and his teeth glimmered like sharp crystals.

“What?” Magnus’s voice shook. “What is it you want?”

“His memories,” said Asmodeus.

“Azazel took a memory from each of us, as payment for a favor,” Alec said. “What is it with you demons and memories?”

“Human memories, freely given, are like food to us,” said Asmodeus. “Demons live on the cries and agony of the damned in torment. Imagine then, how nice a change of pace a feast of happy memories is. Mixed together, they are delicious, the sour and the sweet.” He looked around, his cat’s eyes glittering. “And I can already tell there will be many happy memories to take, little vampire, for you are much loved, are you not?”

Simon looked strained. He said, “But if you take my memories, who will I be? I don’t—”

“Well,” said Asmodeus. “I could take every memory you have and leave you a drooling idiot, I suppose, but really, who wants the memories of a baby? Dull, dull. The question is, what would be the most fun? Memories are delicious, but so is pain. What would cause the most pain to your friends, here? What would remind them to fear the power and the wit of demons?” He clasped his hands behind his back. Each of the buttons of his white suit was carved in the shape of a fly.

“I promised my immortality,” Simon said. “Not my memories. You said ‘freely given’—”

“God in Hell, the banality,” said Asmodeus, and he moved, as swift as a lick of flame, to seize Simon by the forearm. Isabelle darted forward, as if to catch hold of Simon, and then flinched back with a gasp. A red welt had appeared across her cheek. She put her hand to it, looking shocked.

“Leave her alone,” Simon snapped, and wrenched his arm out of the demon’s grip.

“Downworlder,” the demon breathed, and touched his long, spidery fingers to Simon’s cheek. “You must have had a heart that beat so strong in you, when it still beat.”

“Let him go,” Jace said, drawing his sword. “He is ours, not yours; the Nephilim protect what belongs to us—”

“No!” Simon said. He was shivering all over, but his back was straight. “Jace, don’t. This is the only way.”

“Indeed it is,” said Asmodeus. “For none of you can fight a Prince of Hell in his place of power; not even you, Jace Herondale, child of angels, or you, Clarissa Fairchild, with your tricks and runes.” He moved his fingers, slightly; Jace’s sword clattered to the ground, and Jace jerked his hand back, grimacing in pain as if he’d been burned. Asmodeus spared him only a glance before raising his hand again.

“There is the gateway. Look.” He gestured toward the wall, which shimmered and came clear. Through it Clary could see the hazy outlines of the Hall of Accords. There were the bodies of the Endarkened, lying on the ground in heaps of scarlet, and there were the Shadowhunters, running, stumbling, hugging, embracing one another—victory after the battle.

And there were her mother and Luke, looking around in bewilderment. They were still in the same position they had been in on the dais: Luke standing, Jocelyn kneeling with her son’s body in her arms. Other Shadowhunters were only just beginning to glance toward them, surprised, as if they had appeared out of nowhere—which they had.

“There is everything you want,” said Asmodeus, as the gateway flickered and went dark. “And in return I shall take the Daylighter’s immortality, and along with it, his memories of the Shadow World—all his memories of all of you, of all he has learned, of all he has been. That is my desire.”

Simon’s eyes widened; Clary felt her heart give a terrible lurch. Magnus looked as if someone had stabbed him. “There it is,” he whispered. “The trick at the heart of the game. There always is one, with demons.”

Isabelle looked incredulous. “Are you saying you want him to forget us?”

“Everything about you, and that he ever knew you,” said Asmodeus. “I offer you this in exchange. He will live. He will have the life of an ordinary mundane. He will have his family back; his mother, his sister. Friends, school, all the trappings of a normal human life.”

Clary looked at Simon desperately. He was shaking, clenching and unclenching his hands. He said nothing.

“Absolutely not,” said Jace.

“Fine. Then you’ll all die here. You really don’t have much leverage, little Shadowhunter. What are memories when weighed against such a great cost of life?”

“You’re talking about who Simon is,” said Clary. “You’re talking about taking him away from us forever.”

“Yes. Isn’t it delightful?” Asmodeus smiled.

“This is ridiculous,” said Isabelle. “Say you do take his memories. What’s to stop us from tracking him down and telling him about the Shadow World? Introducing him to magic? We did it before, we can do it again.”

“Before, he knew you, knew and trusted Clary,” said Asmodeus. “Now he will know none of you. You will all be strangers to him, and why should he listen to mad strangers? Besides, you know Covenant Law as well as I do. You will be breaking it, telling him about the Shadow World for no reason at all, endangering his life. There were special circumstances before. Now there will not be. The Clave will strip all your runes if you try it.”