Clary stalked across the room, taking a step every few words that she spoke. "I will not stand by you and watch you tear apart everything the Nephilim stand for. We killed Sebastian- stabbed him right through with the angel blade." She pointed at her chest to emphasise her point, though what she was saying was not strictly true. "And now, I want my body back."

"Clary?" Magnus blinked, taking out a demon with his left hand as he turned idly to face her. "Prove that it's you." His eyes sparkled, with both disbelief and hope.

"I… can't. You'll just have to take my word for it." She hesitated to turn back to Lilith, her eyes drifting over Alec's limp body on the stone flooring and the un-hooded head of Brother Zachariah as he took out another demon and took one step closer to Lilith.

Inside Sebastian's body, she stepped forwards again, still creeping back towards her own body, the pull too much to tear herself away from. "I'm done with this- with you. You think you can just walk all over everyone, take my body and get away with it? You think you can take out the Institute and nobody will notice? Bullshit. We dedicate our lives to eradicating this earth of demons like you and this time is no different. And, if you won't give my body up, then I am more than willing to."

She turned her head now, looking up at Brother Zachariah as he took out the last of the demons. "Do it. Kill me- kill her. Destroy my body so she can't use me, trap her in a pyxis and lock her away for a million years. I don't care what it takes to do it… just…"

"Clary?" Magnus was suddenly at her side, resting his hand gently on her shoulder. His voice was soft in her ear, a murmur at most. "What did you do?"

She gulped down a sob, clenching and unclenching her fists at her sides. "I killed Jace."

Brother Zachariah leapt forward with his staff in hand, taking Lilith unawares as she studied the scene between Magnus and Clary- or Sebastian. He swiped the wooden stick sideways with all his might and smashed it into her skull, and Sebastian dropped to the ground in agony, clutching his head. Well that settles it then- it really is Clary, Zachariah thought, as he brought the staff down onto Lilith's chest. She coughed blood, and sticky red liquid oozed onto the tiles beneath Sebastian's crouched figure.

Lilith took one more strike before going down completely, lying still and unmoving on the cold floor. Brother Zachariah tucked his staff into the belt of his robes and looked up at Magnus with a grim expression on his face that said all he needed to know. His eyes widened as another figure appeared at the door, pale and drenched in blood with his hair plastered to his face with sweat- Jace.

"Clary?" He croaked, starting to hobble towards Lilith before crumpling onto the floor just inside the doors, clutching at his chest and wincing as he struggled for breath. Magnus shook his head and fell to the floor, scooping Alec up in his arms and holding him like a child. He struggled from the ballroom, sprinting across the Institute to the infirmary like a bat out of hell. Brother Zachariah scooped up Lilith with the same motion, but carried Clary's body in a calmer, less desperate fashion. He rested his hand on Jace's head as he passed, sending a shock through the boy that seemed to wake him up.

Bring Sebastian. It's important- you'll understand.

As though controlled by Brother Zachariah's words, Jace rose to his feet and shed his bloody shirt, taking a deep breath as the pain in his ribs lessened and the power of the angel blade healed him from the inside. He bent over and lifted Sebastian by the shoulders, picking him and throwing him over his left shoulder. "Whatever you did to Clary, I'll make you pay." He muttered through gritted teeth, struggling under Sebastian's weight as he stepped out into the corridor. "Mark my words."

Magnus was bent over Alec as Jace stepped into the infirmary and dropped Sebastian onto the bed next to Clary. Brother Zachariah had pulled his hood back up over his head and now stood silent at the end of Clary's bed, his staff in hand. Jace Herondale. He began, closing his eyes beneath the hood. The girl that lays on the bed before me is not the Clary you know and love. At the battle in Ireland, Clary was mortally wounded with the blade of a demon. It was enchanted by a warlock practicing dark magic so that it would separate her soul from her body. It is to my belief that this was orchestrated by Lilith, so that she might take over Clary's body and impersonate her in order to obtain Nephilim secrets or such. With shadowhunter blood she was able to access the Institute at will and with Clary's power to create runes, was able to draw the runes you saw on the floor of the ballroom. These runes would spawn demons at her command- and unlimited amount. She could have created an army if Alec, Magnus and I were not there to stop her.

Clary's soul was not trapped like that of a ghost, though they shared much of the same qualities. Clary took with her part of her power, and was able to draw runes on glass without the use of a stele-she was able to portal around the world and, to my understanding, tracked down Sebastian through a mental connection with Lilith. In finding Sebastian, Clary also found Simon and the Angel Blade. The next stage in Sebastian's plan was to wake you from the sleep in which Lilith had placed you, and bring you down here to fight against us and rule the demon army. He never got that far- Simon stabbed him with the Angel sword and removed what was left of his soul from his body. I believe that Sebastian now exists in the same state Clary had- however she was so close to his body that when his soul left, hers was sucked in.

And so Jace, it stands like this. Clary managed to sever the connection between yourself and Sebastian, and by extension Lilith. Alec and myself fought off the first round of demons, but was struck by a claw and is now infected with the demon poison. The fight took so long to finish that Magnus will have to work hard if he is to save him- but he will not let me near to help. It is on his shoulders.

Clary's soul is trapped inside Sebastian's body, and the longer she remains trapped the more damaged her soul will be. She is pure, Clary- good and innocent. Being in touch with a body so contaminated with evil for too long will harm her, I am sure. And, the longer Lilith remains in Clary's body, the higher the risk of Clary's soul returning to a body that is near uninhabitable. Lilith is sneaky- she may have damaged Clary's body in ways we cannot imagine. It is not nearly as simple as it all seems-

"Then I'll leave. Let you do your… thing. I'll…"

Go upstairs. With Lilith so weak, she can't hold up the force that is keeping Maryse and Isabelle subdued. Wake them and bring them down to the library- tell them to await me there.

Brother Zachariah turned his back on Jace and raised his hand, pulling the curtains shut around the two beds with an invisible force. Jace glanced over to Alec as Clary vanished behind the screen, and saw Magnus' pale and worried face.

"Can I…?" he started, but Magnus shook his head.

"I'm too late… I've failed…" His voice was like a cry, an agonising moan that Jace could not bear to hear coming from the mouth of someone he had always considered so strong.

Jace opened his mouth to ask what Magnus meant, but suddenly crumpled to the ground as an immense pain took over his body. The parabatai rune on his shoulder had begun to burn, the pain spiking through his chest and piercing his heart in a million different places. Blood prickled on his skin and ran in lines down his bare skin as he bent on the floor, scrunching up his face in an attempt to bear it. "Alec…" He strained, lifting his head from the bleeding rune to look at his brother.

Alec was pale, the runes on his skin glistening like they weren't completely there. His cheek was red and puffed up with venom, the skin almost bruised with swelling. Magnus clutched his hand as his chest rose and fell with desperation, and his head twisted with agonising hallucinations. Jace struggled to his feet and collapsed on Alec's other side, gripping his parabatai's hand as he prepared to leave the mortal world. "No." He whispered, tightening his grip. "No."