What if Sebastian had succeeded in kidnapping Clary in 'The City Of Glass'? What does would he want her for? Will Jace find her? #CLACE, #SIZZY, #MALEC

"Come outside with me. I'll tell you everything." Sebastian took her wrist, his tone anxious, desperate. "Clary, please."

She shook her head. Why was he being like this? "I have to stay here. I have to wait for Simon. Alec told me they'd be bringing the prisoners here-"

Now Sebastian was shaking his head. "Clary, didn't anyone tell you? They left the prisoners behind. I heard Malachi say so. The city was attacked, and they evacuated the Gard, but they didn't get the prisoners out. Malachi said they were both in league with Valentine anyway. It was agreed that letting them out would be too much of a risk."

At Sebastian's words, Clary saw black spots appear before her eyes, and she felt a little unsteady. "That can't be true."

"It is," Sebastian said. "I swear it is." His grip on Clary's wrist tightened again, and she swayed on her feet. "I can take you there, to the Gard. I'll help you get him out. But you have to promise me that you won't tell anyone."

At this point, Clary was desperate enough to do anything. She had known Simon since before she could remember. He lived in her… she had to save him. "I promise," she told Sebastian.

"Good," he said, and he seized her wrist and dragged her away from the Hall, her family and friends, and up the hill, running towards the treetops near the western wall of the valley. However, Clary realised that he was taking them in the opposite direction to the Gard.

"We're going the wrong way! The Gard is over there," she pointed. Something flickered behind Sebastian's eyes – something there and gone too quickly to identify. Clary felt a chill run up her spine.

"You don't miss much, do you?" Sebastian said. An evil glint came across his jet black eyes, and he produced a needle from his inside pocket, still not letting go of Clary's wrist. In the needle was a thick, clear liquid.

Clary's eyes filled with terror, and she tried frantically to release her arm from Sebastian's grasp. She couldn't – he was too strong.

"Father said you might need restraining," Sebastian hissed, as he grabbed both her arms, twisting them behind her back. He seized the needle and forced it into her neck. "Goodnight, little sister." Overcome with pain, Clary could only form one thought: what did he mean, sister? She was Jace's sister. The last thing she saw was Sebastian's face, contorted with malice, as he pressed the plunger into her neck.

Meanwhile, in the Hall…

Isabelle was getting nervous. When Sebastian had asked to speak to Clary alone, she had thought nothing of it – they all wanted their privacy sometimes. However, when the minutes ticked by, without a glimpse of either of them, she began to worry.

Jace could see Izzy was getting anxious, twisting her hands into the fabric of her skirt. Sebastian and Clary should be back by now; it was getting dark out. Just when Jace was about to suggest they should go out and look for them, Alec spoke up.

"Clary and Sebastian should be back by now," he said. "Let's go and look for them." Jace grinned, despite his worry for his sister. There were certain perks to having a parabatai.

"Sure," Jace said. No one was likely to notice they were missing, not when Alicante was under siege with injured Shadowhunters practically everywhere they stepped. Izzy began to lead the way out of the Hall, when she stopped short.

"Simon," she said.

"Yeah, what about him?" Alec said.

"The prisoners were meant to be taken to the Hall – where are they?"

Jace realised that in all his panic about Clary, he'd forgotten about her vampire friend. Clary was going to kill him if Simon got hurt. "They may have forgotten about the prisoners, what with all this mayhem going on. How about we split up? You and Alec can go and rescue the bloodsucker – bring Magnus just in case; I'll find Clary."

His siblings nodded in agreement, and they split off, Alec, Izzy and Magnus to the Gard, himself to… wherever Clary was. Jace could feel his sister's absence like a splinter lodged in his heart, as he made his way to the exit alone.

A/N: Some dialogue belongs to Cassandra Clare. This is my first fanfiction, so please review and share your feedback. Thanks for reading!