Despite how much I would love to, I don;t own the Infernal Devices Series by Cassandra Clare, which sadly means that I don't own Jem or Will. Nor do I own the Mortal Instruments series by Cassandra Clare, which also means I don't own the very delicious Jace :(

What I DO own is the plot, along with my original characters that you haven't met yet. :)

Full Summary: When the Infernal Devices Cast uncovers a never-before seen rune, it leads them to the future, where they meet the Mortal Instruments Cast. Everything seems to be going great, until problems and people from the past follow them through time into the present. Not to mention that Jem and Jessamine have found something to tether them to at time that is not their own. Will new additions to the main ensemble help defeat the Pandemonium Club and find the missing Downworld leaders? Will the characters from the past remain in the present?

Jem eyed the broken off sliver of glass warily, his silver eyes staring intently at the mirror-like object. "I honestly haven't the slightest clue about how this relates to the Downworlder case," he said with a questioning glance at Will, who was standing next to him, holding a witchlight over Jem's head to illuminate the darkness. They were standing just by the docks, where the air was usually dense and humid. But that night, it was actually clear enough that you could see the stars and inhale the fresh air. Tessa was just several paces back, her mind clearly elsewhere.

"Perhaps there is an inscription on the back," Tessa pointed out. Nodding, Jem cautiously flipped the thin material over, careful to not break it apart. Nothing.

Will, snatched the fragile item from Jem and held it at eye level. "There," he said, touching a faint drawing of sorts, "It appears that it is a rune," Will concluded.

Tessa skittered up to him, their shoulders just barely touching. Tessa had expected him to shy away or tense up, but she no longer gave a care. Though even the slightest touch between them sent shock waves through her body. Jem casually walked over to them, the tapping of his cane on the cobblestone street eerily audible throughout the dark street.

"Are you aware of which rune it is, Will?" asked Jem, who had a curious look about his face.

Shaking his head, Will handed it to Jem, who examined the sharp fragment of glass closely. "I think it may be a rune for foresight," he stated. The bold lines on the rune made the shape of an eye, very much similar to the runes that Will and Jem had on the backs of their hands.

"And that looks like a pathway!" Tessa pointed out. Could it finally be another clue to her heritage?

Will shook his head, a look of disapproval on his face. "No, that is clearly a door." Tessa could tell that he was trying to refrain from speaking her name, holding it back. He no longer welcomed her with a joking smirk and a sarcastic remark, but with a criticizing glare and some insult. She didn't want to think about the details. But did Will truly and deeply no longer have feelings for her?

Just beside her Will swore to himself. How he so desperately wanted to crawl away from Tessa, or to her, perhaps. It somewhat hurt him to say those hurtful things on the widow's walk only several days ago, but he shook it off. Feelings were feelings. And he was a Shadowhunter before anything else. Nevertheless, he felt a stab of pain every time her pushed her away, every time he ignored her, but he had to. A Nephilim and a warlock, together? Rubbish. But every chance he got, whenever Tessa wasn't looking, he'd admire her. Her raw, simplistic beauty, her sense of humor, the way she was so innocent and unaware of the world around her...

"Er... Will? Tessa?" Jem clicked his cane against the ground impatiently, disrupting his friend's train of thought. "Are we to return to the Institute or wait for the rain to come?"

Startled, both Will and Tessa looked to the sky, simultaneously. The once clear sky was clouding up, the gray clouds looking as though they were glowing.

Back in the Institute, the trio was considerably dampened by the rain, which had gone down to a slow drizzle by the time they returned. Like a gentleman, Jem held open the door and ushered Tessa inside with a playful grin, leaving Will scowling outside.

The Institute was a lot more quiet since Thomas and Agatha had died.

Jessamine and Charlotte had volunteered to cook the evening meals, but no one was really doing the maintenance work, considering that Henry was always in his laboratory conducting strange experiments and inventing things and dissecting things, and that Will and Jem were always training or fighting demons or doing whatever it was that boys did. Tessa would have volunteered, but she was no expert when it came to handiwork and fixing things. Sophie had grown much more silent since the deaths of Thomas and Agatha, often keeping to herself and the laundry baskets.

Charlotte often said that she would hire new "replacements" as Will liked to call them, though she never had. The thought of replacing good servants and loyal friends had mortified her, though Will has explained that Charlotte was just having trouble looking for people who wanted to do some unpaid labor.

Tessa looked around the Institute. She remembered how it once appeared glamorous and stunning to her, but now it was plain, ordinary, and in much need of cleaning. She, Jem and Will crept up the stairs and into their rooms, though the sounds of their footsteps was like thunder in the ever-silent church. As Tessa was closing the door to her room, she heard the slight meow of a cat and smiled to herself as the sound of a violin echoed through the hall.

The next morning, Tessa woke to find that Sophie was already in her room, setting down her tea and setting down a white dress with a light blue trim. Just several days after the "clockwork invasion" Jessamine insisted that Tess accompany her to the city and purchase some clothes to clear their minds, which is why there was a new dress neatly placed at the foot of her bed. Seeing that Tessa was awake Sophie shrouded her face with her hair and made for the door, her shoes silent against the hardwood. The girl looked so quivery and disheveled that if Tessa hadn't known better, she would've mistaken her for a ghost.

Not stopping to think, Tessa blurted out a strangled, "Wait!"

Sophie looked up, a dark iris peering out from the hair draped in front of her face.

Gulping, Tessa motioned for her to sit in the chair next to her bed. Sophie walked over groggily and plopped into the seat, her black hair swaying in front of her face. Tessa tried to brush the hair out of Sophie's face, but the girl pulled away, as if touched by flames.

"S-Sophie," Tessa whispered, testing out the name, seeing if Sophie would flinch. But the girl sitting across from her was as silent as ever.

Sophie remained silent.

Giving up, Tessa excused the raven-haired girl. As Sophie hurtled out the door, Tessa caught a glimpse of her eyes, which were red a and puffy. Tessa recognized the attribute, for she had cried multiple times throughout the past couple of months. She would cry for hours, or minutes, or days even. She'd cry whenever she thought of her Aunt, or Nathaniel, or being alone or imprisoned, like at the Dark Sister's old brothel.

Standing up, Tessa strode into the corner, where the bath was. Skimming the water with her fingers, she found that it was already quite warm. Stripping off her nightgown, Tessa stepped into the tub, fighting the urge to thrust her head underwater and keep it there.

Once she had change into the blue dress, Tessa sat in the chair in front of the vanity mirror and looked at the reflection of herself. She had gained a bit of weight since she escaped from the brothel, which was good, in a sense. Her once bone-thin wrists had filled out a bit, and the color had started coming back to her face. Dark circlets still remained under her eyes, and Tessa could see bruises on her arms from where she had been brutally manhandled by the clockwork creatures. In her reflection she only saw bits and fragments of Tessa Gray. She recognized the light gray eyes and the plain brown hair, but everything else seemed different.

Tessa looked away from the mirror and down at her chest, where only days ago she had stabbed herself, or pretended to stab herself. Sometimes she hoped that she had really just drove the knife into her heart and spared herself the heartache that surrounded her now. After all, it wouldn't be very long until the Magister had found out that she was alive and tried to steal her away again.

Standing up, Tessa looked away from her mirror and found herself making her way to the door and to the dining room, where Henry and the other Shadowhunters were patiently awaiting her presence.

Much to her disappointment, Tessa found that there was no breakfast on the table. There was only the broken shard that Jem and Will had discovered the other night. All of the Nephilim had crowded around the table, and more importantly, Henry.

"May I have everyone's attention!" Henry said, everyone turning their eyes onto him. Well, almost everyone. Will was staring off into the distance, and Jessamine was looking at her feet.

Charlotte cleared her throat, and five pairs of eyes glanced up at her. She gave a slight nod to Henry, who began speaking. "Friends and dearest wife, after hours of studying this fragment of what I believe to be a mirror and comparing the rune printed on it-."

"Just tell us what you came up with," Will interrupted with a growl. His expression was full of impatience. Classic Will. Charlotte gave him a look of scorn and paid her attention back to Henry, who appeared as if he were about to burst with excitement.

"Please continue, darling."

Though the room was quite chilly, Henry wiped a bead of sweat that was rolling down his forehead. Church the cat, who was sitting on Jem's lap, could even sense Henry's nervousness. His hands were trembling and he had to place the piece of mirror onto the table before he dropped it. "You may not believe it, but... uh," Henry started.

"Get on it with it, then!" Jessamine shouted. She slammed a gloved hand onto the table, with shook fiercely.

Tessa was surprised. Henry wasn't often as jittery and nervous as he was now. She had lived in the Institute for almost several weeks now, and even she knew Henry was full of energy. He never could hold back introducing a new invention, or idea. But right then, he had that same excited looked in his green eyes, though the rest of his body told the others another story.

Charlotte gave another heart-stopping glare and sent it to Jessamine, who rolled her eyes.

"As I was saying, after careful examination, I discovered that the rune on this chunk of mirror is, as James here first predicted, the rune of foresight. But the rune behind it was an Open rune."

"So what has that got to do with anything?" Jessamine questioned.

"It could mean a lot of things. Foresight open, future open, foresight unlocked..." Will piped from his seat, directly across from Jessamine.

Jem looked up from Church, who purred loudly. "Or future unlocked," he finished.

So that was my entire first chapter! And before you point it out, yes I know it was kind of short, but I really wanted to get this idea down before it went away. Hopefully I'll have a longer chapter by this weekend or next week, but who knows? Anyways, pretty, pretty PLEASE R&R!

P.S. I understand that there have been MANY crossovers with MI & ID, but I hope to make one slightly different (or considering how many X-overs there are with this a story with combined concepts) than the others. I just really wanted to get this idea over and done with. XP