Amatis turned and looked over her shoulder at the Shadowhunters. Her gaze caught on her brother’s for just a moment; her lip curled. It was a vicious look. “Do it,” she said. “Kneel, or I will kill you.”

Magnus knelt first. Clary would never have guessed that. Magnus was so proud, but then it was a pride that transcended the emptiness of gestures. She doubted it would shame him to kneel when it meant nothing to him. He went down on his knees, gracefully, and Alec followed him down; then Isabelle, then Simon, then Luke, drawing Clary’s mother down beside him. And lastly Jace, his blond head bowed, went to his knees, and Clary heard the window behind her shatter into pieces. It sounded like her breaking heart.

Glass rained down; behind it was bare stone. There was no longer any window that led to Alicante.

“It is done. The paths between the worlds are closed.” Sebastian wasn’t smiling, but he looked—incandescent. As if he were blazing. The circle of runes on the floor was shimmering with blue fire. He ran toward the platform, took the steps two at a time, and reached up to catch Clary’s hands; she let him draw her down from the throne, until she stood in front of him. He was still holding her. His hands felt like bracelets of fire around her wrists. “You accept it,” he said. “You accept your choice?”

“I accept it,” she said, forcing herself to look at him with absolute directness. “I do.”

“Then kiss me,” he said. “Kiss me like you love me.”

Her stomach tightened. She had been expecting this, but it was like expecting a blow to the face: Nothing could prepare you. Her face searched his; in some other world, some other time, some other brother was smiling across the grass at her, eyes as green as springtime. She tried to smile. “In front of everyone? I don’t think—”

“We have to show them,” he said, and his face was as immovable as an angel pronouncing a sentencing. “That we are unified. Prove yourself, Clarissa.”

She leaned toward him; he shivered. “Please,” she said. “Put your arms around me.”

She caught a flash of something in his eyes—vulnerability, surprise at being asked—before his arms came up around her. He drew her close; she laid one hand on his shoulder. Her other hand slid to her waist, where Heosphoros rested with its scabbard tucked into the belt of her gear. Her fingers curled around the back of his neck. His eyes were wide; she could see his heartbeat, pulsing in his throat.

“Now, Clary,” he said, and she leaned up, touching her lips to his face. She felt him shudder against her as she whispered, her lips moving against his cheek.

“Hail, master,” she said, and saw his eyes widen, just as she pulled Heosphoros free and brought it up in a bright arc, the blade slamming through his rib cage, the tip positioned to pierce his heart.

Sebastian gasped, and spasmed in her arms; he staggered back, the hilt of the blade protruding from his chest. His eyes were wide, and for a moment she saw the shock of betrayal in them, shock and pain, and it actually hurt; it hurt somewhere down deep in a place she thought she had buried long ago, a place that mourned the brother he might have been.

“Clary,” he gasped, starting to straighten, and now the look of betrayal in his eyes was fading, and she saw the beginning spark of rage. It hadn’t worked, she thought in terror; it hadn’t worked, and even if the borders between the worlds were sealed now, he would take it out on her, on her friends, her family, on Jace. “You know better,” he said, reaching down to grasp the hilt of the sword in his hand. “I can’t be hurt, not by any weapon under Heaven—”

He gasped, and broke off. His hands had closed around the hilt, just above the wound in his chest. There was no blood, but there was a flash of red, a spark—fire. The wound was beginning to burn. “What—is—this?” he demanded through clenched teeth.

“‘And I will give him the Morning Star,’” Clary said. “It’s not a weapon that was made under Heaven. It is Heaven’s fire.”

With a scream he pulled the sword free. He gave the hilt, with its hammered pattern of stars, one incredulous look before he blazed up like a seraph blade. Clary staggered back, tripped over the edge of the steps to the throne, and threw one arm partly over her face. He was burning, burning like the pillar of fire that went before the Israelites. She could still see Sebastian within the flames, but they were around him, consuming him in their white light, turning him to an outline of dark char within a flame so bright, it seared her eyes.

Clary looked away, burying her face in her arm. Her mind raced back through that night when she had come to Jace through the flames, and kissed him and told him to trust her. And he had, even when she had knelt down in front of him and driven the point of Heosphoros into the ground. All around it she had drawn the same rune over and over with her stele—the rune she had once seen, it felt like so long ago now, on a rooftop in Manhattan: the winged hilt of an angel’s sword.

A gift from Ithuriel, she guessed, who had given her so many gifts. The image had rested in her mind until she’d needed it. The rune for shaping Heaven’s fire. That night on the demon plain, the blaze all around them had evaporated, drawn into the blade of Heosphoros, until the metal had burned and glowed and sung when she’d touched it, the sound of angelic choruses. The fire had left behind only a wide circle of sand fused into glass, a substance that had glowed like the surface of the lake she had so often dreamed about, the frozen lake where Jace and Sebastian had battled to the death in her nightmares.

This weapon could kill Sebastian, she had said. Jace had been more dubious, careful. He had tried to take it from her, but the light had died in it when he’d touched it. It reacted only to her, the one who had created it. She had agreed that they had to be cautious, in case it didn’t work. It seemed the height of hubris to imagine she had trapped holy fire in a weapon, the way that fire had been trapped in the blade of Glorious. . . .

But the Angel gave you this gift to create, Jace had said. And do we not have his blood in our veins?

Whatever the blade had sung with, it was gone now, gone into her brother. Clary could hear Sebastian screaming, and over that, the cries of the Endarkened. A burning wind blew past her, carrying with it the tang of ancient deserts, of a place where miracles were common and the divine was manifest in fire.

The noise stopped as suddenly as it had started. The dais shook under Clary as a weight collapsed onto it. She looked up and saw that the fire was gone, though the ground was scarred and both thrones looked blackened, the gold on them no longer bright but charred and burned and melted.

Sebastian lay a few feet away from her, on his back. There was a great blackened hole across the front of his chest. He turned his head toward her, his face taut and white with pain, and her heart contracted.

His eyes were green.

The strength in her legs gave out. She collapsed to the dais on her knees. “You,” he whispered, and she stared at him in horrified fascination, unable to look away from what she had wrought. His face was utterly without color, like paper stretched over bone. She didn’t dare to look down at his chest, where his jacket had fallen away; she could see the stain of blackness across his shirt, like a spill of acid. “You put . . . the heavenly fire . . . into the blade of the sword,” he said. “It was . . . cleverly done.”