"And Sebastian," said Clary.

"But Jace," Alec said. "How was-I mean, how did he seem?"

Clary knew exactly what he was asking; for once she and Alec understood each other better than anyone else in the room. "He's not playing a trick on Sebastian," she replied softly. "He really has changed. He isn't like himself at all."

"How?" Alec demanded, with an odd blend of anger and vulnerability. "How is he different?"

There was a hole in the knee of Clary's jeans; she picked at it, scraping the skin underneath. "The way he talks-he believes in Sebastian. Believes in what he's doing, whatever that is. I reminded him that Sebastian killed Max, and he didn't even seem to care." Her voice cracked. "He said Sebastian was just as much his brother as Max was."

Alec whitened, the red spots on his cheeks standing out like bloodstains. "Did he say anything about me? Or Izzy? Did he ask about us?"

Clary shook her head, hardly able to stand the look on Alec's face. Out of the corner of her eye, she could see Magnus watching Alec too, his face almost blank with sadness. She wondered if he was jealous of Jace still, or just hurt on Alec's behalf.

"Why did he come to your house?" Alec shook his head. "I don't get it."

"He wanted me to come with him. To join him and Sebastian. I guess he wants their evil little duo to be an evil little trio." She shrugged. "Maybe he's lonely. Sebastian can't be the greatest company."

"We don't know that. He could be absolutely fantastic at Scrabble," said Magnus.

"He's a murdering psychopath," said Alec flatly. "And Jace knows it."

"But Jace isn't Jace right now-," Magnus began, and broke off as the phone rang. "I'll get that. Who knows who else might be on the run from the Clave and need a place to stay? It's not like there are hotels in this city." He padded off toward the kitchen.

Alec flung himself down on the sofa. "He's working too hard," he said, looking worriedly after his boyfriend. "He's been up all night every night trying to decipher those runes."

"Is the Clave employing him?" Jocelyn wanted to know.

"No," Alec said slowly. "He's doing it for me. Because of what Jace means to me." He raised his sleeve, showing Jocelyn the parabatai rune on his inner forearm.

"You knew Jace wasn't dead," Clary said, her mind beginning to tick over thoughts. "Because you're parabatai, because of that tie between you. But you said you felt something wrong."

"Because he's possessed," Jocelyn said. "It's changed him. Valentine said that when Luke became a Downworlder, he felt it. That sense of wrongness."

Alec shook his head. "But when Jace was possessed by Lilith, I didn't feel it," he said. "Now I can feel something... wrong. Something off." He looked down at his shoes. "You can feel it when your parabatai dies-like there was a cord tying you to something and it has snapped, and now you're falling." He looked at Clary. "I felt it, once, in Idris, during the battle. But it was so brief-and when I returned to Alicante, Jace was alive. I convinced myself I had imagined it."

Clary shook her head, thinking of Jace and the blood-soaked sand by Lake Lyn. You didn't.

"What I feel now is different," he went on. "I feel like he's absent from the world but not dead. Not imprisoned... Just not here."

"That's just it," Clary said. "Both times I've seen him and Sebastian, they've vanished into thin air. No Portal, just one minute they were here and the next they were gone."

"When you talk about there or here," said Magnus, coming back into the room with a yawn, "and this world and that world, what you're talking about are dimensions. There are only a few warlocks who can do dimensional magic. My old friend Ragnor could. Dimensions don't lie side by side-they're folded together, like paper. Where they intersect, dimensional pockets can be created that prevent magic from being able to find you. After all, you're not here-you're there."

"Maybe that's why we can't track him? Why Alec can't feel him?" said Clary.

"Could be." Magnus sounded almost impressed. "It would mean there's literally no way to find them if they don't want to be found. And no way to get a message back to us if you did find them. That's complicated, expensive magic. Sebastian must have some connections-" The door buzzer sounded, and they all jumped. Magnus rolled his eyes. "Everyone calm down," he said, and vanished into the entryway. He was back a moment later with a man wrapped in a long parchment-colored robe, the back and sides inked with patterns of runes in dark red-brown. Though his hood was up, shadowing his face, he looked completely dry, as if not a flake of snow had fallen on him. When he pushed the hood back, Clary was not at all surprised to see the face of Brother Zachariah.

Jocelyn set her mug down suddenly on the coffee table. She was looking at the Silent Brother. With his hood pushed back, you could see his dark hair, but his face was shadowed so that Clary could not see his eyes, only his high, rune-scarred cheekbones. "You," Jocelyn said, her voice trailing off. "But Magnus told me that you would never-"

Unexpected events call for unexpected measures. Brother Zachariah's voice floated out, touching the inside of Clary's head; she knew from the expressions on the faces of the others that they could hear him too. I will say nothing to the Clave or Council of anything that transpires tonight. If the chance comes before me to save the last of the Herondale bloodline, I consider that of higher importance than the fealty I render the Clave.

"So that's settled," Magnus said. He made a strange pair with the Silent Brother beside him, one of them pale and blanched in robes, the other in bright yellow pajamas. "Any new insight into Lilith's runes?"

I have studied the runes carefully and listened to all the testimony given in the Council, said Brother Zachariah. I believe that her ritual was twofold. First she used the Daylighter's bite to revive Jonathan Morgenstern's consciousness. His body was still weak, but his mind and will were alive. I believe that when Jace Herondale was left alone on the roof with him, Jonathan drew on the power of Lilith's runes and forced Jace to enter the enspelled circle that surrounded him. At that point Jace's will would have been subject to his. I believe he would have drawn on Jace's blood for the strength to rise and escape the roof, taking Jace with him.

"And somehow all that created a connection between them?" Clary said. "Because when my mother stabbed Sebastian, Jace started to bleed."

Yes. What Lilith did was a sort of twinning ritual, not unlike our own parabatai ceremony but much more powerful and dangerous. The two are now bound inextricably. Should one die, the other will follow. No weapon in this world can wound only one of them.

"When you say they're bound inextricably," Alec said, leaning forward, "does that mean-I mean, Jace hates Sebastian. Sebastian murdered our brother."

"And I don't see how Sebastian can be all that fond of Jace, either. He was horribly jealous of him all his life. He thought Jace was Valentine's favorite," added Clary.

"Not to mention," Magnus noted, "that Jace killed him. That would put anyone off."

"It's like Jace doesn't remember that any of these things happened," Clary said in frustration. "No, not like he doesn't remember them-like he doesn't believe them."

He remembers them. But the power of the binding is such that Jace's thoughts will pass over and around those facts, like water passing around rocks in a riverbed. It was like the spell that Magnus cast upon your mind, Clarissa. When you saw pieces of the Invisible World, your mind would reject them, turn away from them. There is no point reasoning with Jace about Jonathan. The truth cannot break their connection.

Clary thought of what had happened when she had reminded Jace that Sebastian had killed Max, how his face had temporarily furrowed in thought, then smoothed out as if he had forgotten what she had said as quickly as she'd said it.

Take some small comfort in the fact that Jonathan Morgenstern is as bound as your Jace is. He cannot harm or hurt Jace, nor would he want to, Zachariah added.

Alec threw his hands up. "So they love each other now? They're best friends?" The hurt and jealousy was plain in his tone.

No. They are each other now. They see as the other sees. They know the other is somehow indispensable to them. Sebastian is the leader, the primary of the two. What he believes, Jace will believe. What he wants, Jace will do.

"So he's possessed," Alec said flatly.

In a possession there is often some part of the person's original consciousness left intact. Those who have been possessed speak of watching their own actions from the outside, crying out but unable to be heard. But Jace is fully inhabiting his body and mind. He believes himself sane. He believes that this is what he wants.

"So what did he want from me?" Clary demanded in a shaking voice. "Why did he come to my room tonight?" She hoped her cheeks didn't burn. She tried to push back the memory of kissing him, the pressure of his body against hers in the bed.

He still loves you, said Brother Zachariah, and his voice was surprisingly gentle. You are the central point about which his world spins. That has not changed.

"And that's why we had to leave," Jocelyn said tensely. "He'll come back for her. We couldn't stay at the police station. I don't know where will be safe-"

"Here," Magnus said. "I can put up wards that will keep Jace and Sebastian out."

Clary saw relief flood her mother's eyes. "Thank you," Jocelyn said.

Magnus waved an arm. "It's a privilege. I do love fending off angry Shadowhunters, especially of the possessed variety."

He is not possessed, Brother Zachariah reminded them.

"Semantics," said Magnus. "The question is, what are the two of them up to? What are they planning?"

"Clary said that when she saw them in the library, Sebastian told Jace he'd be running the Institute soon enough," said Alec. "So they're up to something."

"Carrying on Valentine's work, probably," said Magnus. "Down with Downworlders, kill all recalcitrant Shadowhunters, blah blah."

"Maybe." Clary wasn't sure. "Jace said something about Sebastian serving a greater cause."

"The Angel only knows what that indicates," Jocelyn said. "I was married to a zealot for years. I know what 'a greater cause' means. It means torturing the innocent, brutal murder, turning your back on your former friends, all in the name of something that you believe is bigger than yourself but is no more than greed and childishness dressed up in fanciful language."

"Mom," Clary protested, worried to hear Jocelyn sound so bitter.

But Jocelyn was looking at Brother Zachariah. "You said no weapon in this world can wound only one of them," she said. "No weapon you know of..."

Magnus's eyes glowed suddenly, like a cat's when caught in a beam of light. "You think..."

"The Iron Sisters," said Jocelyn. "They are the experts on weapons and weaponry. They might perhaps have an answer."

The Iron Sisters, Clary knew, were the sister sect to the Silent Brothers; unlike their brethren, they did not have their mouths or eyes sewed shut but instead lived in almost total solitude in a fortress whose location was unknown. They were not fighters-they were creators, the hands who shaped the weapons, the steles, the seraph blades that kept the Shadowhunters alive. There were runes only they could carve, and only they knew the secrets of molding the silvery-white substance called adamas into demon towers, steles, and witchlight rune-stones. Rarely seen, they did not attend Council meetings or venture into Alicante.

It is possible, Brother Zachariah said after a long pause.

"If Sebastian could be killed-if there is a weapon that could kill him but leave Jace alive-does that mean Jace would be free of his influence?" Clary asked.

There was an even longer pause. Then, Yes, said Brother Zachariah. That would be the most likely outcome.

"Then, we should go to see the Sisters." Exhaustion hung on Clary like a cloak, weighting her eyes, souring the taste in her mouth. She rubbed her eyes, trying to scrub it away. "Now."

"I can't go," said Magnus. "Only female Shadowhunters can enter the Adamant Citadel."

"And you're not going," Jocelyn said to Clary in her sternest No-you-are-not-going-out-clubbing-with-Simon-after-midnight voice. "You're safer here, where you're warded."

"Isabelle," said Alec. "Isabelle can go."

"Do you have any idea where she is?" Clary said.

"Home, I'd imagine," said Alec, one shoulder lifting in a shrug. "I can call her-"

"I'll take care of it," Magnus said, smoothly removing his cell phone from his pocket and punching in a text with the skill of the long-practiced. "It's late, and we don't need to wake her up. Everyone needs rest. If I'm to send any of you through to the Iron Sisters, it will be tomorrow."

"I'll go with Isabelle," Jocelyn said. "No one's looking for me specifically, and it's better that she not go alone. Even if I'm not technically a Shadowhunter, I was once. It's only required that one of us be in good standing."

"This isn't fair," Clary said.

Her mother didn't even look at her. "Clary..."

Clary rose to her feet. "I've been practically a prisoner for the past two weeks," she said in a shaking voice. "The Clave wouldn't let me look for Jace. And now that he came to me-to me-you won't even let me come with you to the Iron Sisters-"

"It isn't safe. Jace is probably tracking you-"

Clary lost it. "Every time you try to keep me safe, you wreck my life!"

"No, the more involved you get with Jace the more you wreck your life!" her mother snapped back. "Every risk you've taken, every danger you've been in, is because of him! He held a knife to your throat, Clarissa-"