A/N: Thanks for clicking to read this story and I will do my best to make it good! So I decided to write my first crossover (a bit too early for me I think) because my school break is almost over and I'm worried I won't be able to update for a long time. This is why I wanted to get it out there already and try to do the best I can in the short amount of time I have. My goal is maybe three chapters to five posted already. I hope that you'll review this because I'm paranoid when it comes to writing, so please ease my fears! Thank you!

With that out of the way I shall now present to you my story.

Disclaimer: I am not Cassandra Clare and I even if I wish really hard, it won't happen.

-Chapter one-

William Herondale thrust the blade into the heart of the demon- if they even had one -and he was rewarded with a satisfying sound of tearing and the fillings of the dummy to spill. He jumped back and waited. He heard a lock click into place beside him and he threw the seraph blade he was holding. The dagger embedded itself into the dummy swinging towards him and Will watched as its filling spilled onto the floor like blood. He was in the training room, passing time before he had dinner and to avoid the outside world. He didn't want to talk to anyone and he especially didn't want to talk to Tessa.


A click came and he could only be happy to throw another dagger to its direction to forget her. He heard two locks this time and he looked up to see two dummies coming at him from his sides. He looked down at himself and saw that he only had two seraph blades left. He took them both and ducked down. The dummies hit each other as he whispered into the blades and then, with a flare of heavenly white light, he sliced through them in a fraction of a second. He straightened and looked down at the floor. That was his mistake as his memories rushed into him and he remembered the last time they talked.

Tessa had left, obviously insulted, and Will was glad to see her leave for, after all, it was for her own good.

However, it had hurt him in a way he didn't expect and he couldn't bear the silence she gave him after. Will could feel the walls of his resolve weakening and he found out that the more he tried to rebuild it, the more it would weaken and the less it would keep everyone around him safe from himself.

Another click and Will sighed as he threw the seraph blade- without looking up -and heard that familiar tearing sound again, but he could hear another tearing with it.

The tearing of his heart.

Will smiled at himself at how pathetic he had become. He was turning into one of those men in Tessa's favourite book, A Tale of Two Cities. Will strapped the last dagger into his gear as he thought about it. I wonder if I will I get my head chopped off anytime soon? He went around the large stone room that was bare of anything- even windows -other than Henry's contraptions for their training. Will picked up the seraph blades and strapped them on as he made his way to the door. As he opened the door, he heard Charlotte's raised voice.

"Will," he saw her almost child-like figure approach him and saw the urgency in her brown eyes, "there's demons causing havoc at Whitechapel Street" she was already in her gear.

Will's eyes widened and he closed the door behind him. "I'll get the carriage ready" Charlotte nodded.

"Thank you. I'll go get Sophie and Tessa" Will froze at her name and called back Charlotte before she could go.

"What?" he yelled at her and Charlotte was startled by his reaction. "Are you seriously taking them demon hunting with-"

"I'm going to drop them off somewhere safe, probably at the Lightwoods" Charlotte cut him off and Will almost growled at the name Lightwood. "There is a high possibility the Magister is behind this and I don't want them alone here again. You know what happened last time Will" the boy considered Charlotte's words with clenched his fists but nevertheless agreed. Charlotte saw him nod and told him that another carriage was already waiting outside then ran off to get Tessa and Sophie while Will ran to get the other carriage.

He had prepared the carriages outside when Jem had appeared on the Institute's steps. He looked healthier than usual, a red colour staining his cheeks, but Will knew that was because he took the medicine- the medicine that slowly killed him -in huge amounts so he can fight. Will hated it when Jem had to fight, but it was his parabatai's wish and he respected Jem enough to allow him to do what he desired. "Ready?" he asked him and Jem smiled at him. He said something in his native tongue and Will cocked an eyebrow.

Jem chuckled as he went over to Will. "I was saying that we are always ready" Will smiled and he saw the doors open and Henry and Jessamine appeared. Henry was in his gear while Jessamine, as is Jessamine, was wearing a dress. The boy always insulted the girl for her lack of commitment to being a Shadowhunter and that he didn't just do to keep people away from him.

"Why Jessie, whatever are you wearing?" Will asked in an incredulous voice and she ignored him and climbed into the carriage that he wasn't leaning on. Will smirked and looked at Henry. "Henry, I need you to create more dummies for me after this. I do believe I have obliterated the lot of them" Henry grinned at him and climbed into the driver's seat of the carriage Jessamine was in. Will noticed that everyone was choosing the other carriage and frowned. "Why is everyone going there? Are you all avoiding me?" he looked at Jem. "Tell me the truth James"

Jem laughed despite the situation. "If you keep treating everyone like so, everyone will avoid you" Will decided to play along when he saw the doors open again and Charlotte, Sophie and Tessa appeared. Will could feel his heart start to beat erratically at the sight of her and he thought of something to say to keep him distracted.

"Charlotte! I have fixed the carriages for you. Do you think I have done a good job?" Charlotte looked at him with raised eyebrows and a shocked expression and Will smiled like a proud child at the same time ignoring Tessa who was looking at the ground.

"Uh….." Charlotte thought out her answer to Will's unusual question, "yes you have" she said in an uncertain voice and Will frowned again. Charlotte cleared her throat. "Alright, let's go before anyone could get hurt" she ran towards the carriage Jessamine and Henry has picked and got on. Will turned to Jem and gave him an irritated look which Jem shrugged off. Will climbed onto the driver's seat as Sophie and Tessa got into the carriage but he didn't miss out on the fact that Jem helped them up and Will's eyes narrowed as his friend's hand made contact with Tessa's. He saw her give Jem a smile and Will whipped his head around in silent fury.

A few days ago, Jem had kissed Tessa's hand on the Institute's steps and Will just looked at them as they bid goodbye to each other. It had hurt him and for that moment he was secretly angry with Jem. He's secretly angry with him now too. Jem climbed onto the driver's seat and Will looked at him as if he was sprouting horns on his head. "What are you doing up here?" he asked in an incredulous tone.

Jem placed his cane between his legs as he smiled at him. "You didn't actually think I was going to stay in the carriage did you? I prefer it up here" Will rolled his eyes and gathered the reins. He commanded the horses forward and the carriage rolled to their first destination.

Tessa waited patiently inside the carriage as they rode to the Lightwoods' estate in London on the way to Whitechapel Street. Charlotte had told her they were to be kept there just in case Mortmain had planned the demon attack and he'd appear at the Institute again. Tessa could only be happy to go, but what unnerved her was Will's presence even if it was only for a short time. She had studiously ignored him everyday since that night in the attic and his mere presence at the table made her uncomfortable. Now he was with her again and she tried to keep herself in composure. She didn't want him to see how he'd affected her. Tessa sighed to herself as she looked at her clasped hands shaking in the cold and her situation. Stop it she commanded herself and she soon calmed down. She looked up to see Sophie across from her, her head bowed, and Tessa could see her red eyes despite the dark. The servant girl had gone through a lot and Tessa wished she could do something to ease the other girl's pain.

But she didn't know how to and Tessa looked out the carriage window in despair. She had only taken from these people and to make matters worse, she had caused them to lose two companions. She was a burden. She sighed internally as she looked at the Thames outside. She stared at its murky depths and at the moonlight that glinted of its surface, turning the water into silver. They passed many houses as the carriage rattled on the cobblestone road and she saw some beggars but she also noticed the ones that were part of the world she found herself tangled in. She could tell that they were vampires by the way they walk and she could notice their twisted faces and their mischievous smiles, showing off their fangs that glinted in the moonlight. Tessa was glad when they had finally passed the Downworlders and she was now staring at the full moon.

Suddenly, a blinding white light appeared from nowhere and the carriage stopped. Tessa would have been thrown forward had she not grasped at her seat at the last second to stop her body from falling off her seat. Her body snapped back up and she gasped as her breath got knocked out of her. "What?" Sophie had looked up, startled, and her face was creased in worry as she clutched at the seat to steady herself. Tessa could hear the horses making panicked noises outside and she could hear Will, Jem and Henry exclaim over them. She then heard a thud on the roof and heard Jem shout at Will. Tessa looked at Sophie and she screamed at what was behind Tessa. The girl's head snapped toward the direction and saw the back part of the carriage on fire. "Miss Grey!" Sophie exclaimed and Tessa moved to her side of the carriage at the same time that the carriage door opened. Jem stood at the entrance, his cane in his hand and his silver eyes bright. Beyond him, Tessa could make out small ropes of fire surrounding the carriage.

"Get off!" he told them and Tessa jumped out of the carriage followed soon after by Sophie. Jem took them to a safe distance away and Tessa looked back at the carriage to see Will on the roof and flames were around him. From where Tessa was standing, he looked like an angel in the middle of the burning hell. He seemed to be looking for something in the distance when Jem shouted at him to get off. Will jumped off the carriage and landed silently and when he straightened, Tessa could see the fury in his blue eyes despite the distance between them. "Henry!" Tessa looked at Jem who had left them and was now helping Henry, who got tangled by the reins, out of the seat while Jessamine and Charlotte climbed out. Jessamine was gasping and there was a part of her dress that was burnt and Charlotte was staring.

"What in the name of the Angel is happening?" Charlotte asked as she saw the two carriages on fire. She looked at Henry, Jem and Will as they made their way towards them, "I saw a bright light then all of a sudden everyone was screaming" she looked at Will. "What happened?"

"Exactly like you said then I saw a rope of fire get thrown towards us. It bounced into the carriage roof then it was in flames in an instant" he said in an impatient tone and they all watched as the carriages burned.

"Could this be Mortmain?" Tessa found herself ask and they all looked at her in what seemed like silent agreement.

Everyone except Jessamine who stared open-mouthed at her dress "Who cares?" she screamed as she looked up at Tessa. "The carriages are on fire and we still need to get to the Lightwoods and look!" she pointed to the blackened part of her dress. "My dress is a disgrace and I am a lady and I will not walk around in the night like this!"

Tessa could feel her fists clench. She's had enough of Jessamine. "We were almost burnt down into nothing but ashes and all you care about is your stupid dress? Have you any-" Tessa's words were cut off when she felt a sudden sharp pain at her chest. Charlotte looked at her and gasped. Everyone else did too and they stared. Tessa looked down and saw a hilt of a knife protruding through her chest, her blood soaking her dress. She looked up to see everyone still stare at her as if they were too numb to do anything else. Tessa didn't see it coming and now she could taste her blood in her mouth and she looked beyond the Shadowhunters and Sophie to see a dark figure on top of the burning carriages.

There was someone there who was crouching and he raised his head and Tessa realized that it wasn't a man after all, but a woman. She had white-gold hair and as she looked at Tessa, and Tessa looked back, she saw a pair of bicoloured eyes. One gold and one pitch-black. The woman smiled at her maliciously and Tessa could hear her slowing heartbeats as the woman hopped off the carriage and as everyone went to her.

She could hear them screaming her name as she fell into Will's arms. She could see them look around for who had thrown the dagger and she could see Will, his beautiful blue eyes blank and staring, his face void of any emotion as he held her.

Tessa could hear them faintly over the thud of her pulse in her ears and she could feel the pain start to lose its grip on her, but a new one clung to her even more tightly. It was the grip of death. Despite this, she heard Charlotte scream once more and Jem shout something. She saw things glint through her blurred vision and dark figures approached the Shadowhunters. She could see them start to fight, brandishing their blades in rage at a lost companion. Will had long moved away from her and fought too and she looked at him as he fought the dark hooded figures before she heard one final beat and her eyes closed.