THE TITLE : Skeleton Key

THE RATING : Teen +

THE GENRE : All / Romance

THE TYPE : Crossover

CROSSOVER : The Mortal Instruments / Buffy the Vampire Slayer

KEY PAIRINGS : Jace / OC

SUMMARY : Jace and the team are on the hunt looking for some vampires that have broken the accords - while on the hunt they meat someone unexpected .

DISCLAIMER : I do not own canon content of anything from The Mortal Instruments or Buffy the Vampire slayer - I mearely own the plot for this story and any original content within it.

AUTHORS NOTES : I just want to let everyone know I have only read City of Bones and just started on City of Ashes, this idea came to me while reading and watching buffy the vampire slayer, I apologize in advance for any errors i make with anything involving The Mortal Instruments series. But this is my own story/idea so things won't be a 100 % canon - but fanfiction is meant to be not canon. So my story is taking place Post - City of Bones. Also most of you may also know that City Of Bones will be turned into a film you may agree or not agree on their casting but personally I am 50/50 with their choices in casting so I will leave canon characters up to your imaginations - as for my story, and my lead original character Aderes will be portrayed by: "Taylor Momsen." - If you don't know her you can google her or search her in whatever way you search.

I .) CHASING SHADOWS

The clatter of feet on the cement ground sounded from an alley behind a newly opened club that was packed beyond the brim with people, with people still be waiting to be let inside, but the sounds of fighting and scattering in the alley were drowned out by the usual new york noise and the sounds coming from within the club that was dubbed "Spirits". The blond currently in the alley fighting off several Children of Lilith had been enjoying the new club and what it had to offer - but that had been cut short when her "vampy senses" started tingling and alerted her to the blood suckers that had been in the club - They must have charmed their way in because they were in now way passable for teenagers. Her pale skin was smeared with grime of the alley, cuts mixed in with the dirt and blood - she was some sight to clothes torn and ripped as she jumped back into the fray of the fight, not about to let a few fanged asses get the upper-hand and slip away from her. If it were a normal day, she just looked like trouble with an attitude problem.

Aderes however could pass for a girl sweet and innocent if she happened to change her wardrobe and stuck a few berets in her hair and wiped off some of the make up she wore. But she appeared either way to be a normal girl either who took the wrong path and went to the wrong side to the tracks... Which was half true but not the complete story. Aderes wasn't your everyday teenager, she was a slayer of all things that were bad. Vampires being one of them. She was granted with the gift to roam graveyards at night instead of the theater with her friends. Not that she had many friends. She kept people at a distance, The blond couldn't risk people finding out her nighttime pastime. As usual though her attempt to be normal was cast down the drain by a couple of hungry blood suckers.

"Why for once can't you jackasses stay in your coffins?" She asked looking at them and sighed, "you actually think your scary.. I mean seriously is that a lace collar? Man you're way out of date with your clothes."

She said looking at them. The vampires couldn't help but look at her the one with the lace collar looking down at it then back at her and tilting its head. The four were confused. She seemed like an ordinary mundane, She was no shadow hunter yet something about her set them on edge. Put them on guard. The didn't know how she had managed to lure them out of the club through the back. They had though she was and easy meal till she had turned one of their friends to dust, which was now scattered and couldn't be differentiated between the loose gravel and dirt on the ground due to the scuffling and fighting that had been occurring between them. She had power beyond what someone who appeared to be a mundane should not have - They had tossed her into a wall and she got up like it was barely nothing, as if it had just been a paper cut. The suspected her to drop where she stood, she should have been exhausted but she stood before them barely out of breath. Mocking them - It was unsettling.

Clary had been standing in line with Simon, Isabelle, Alec, and her new found brother, Jace for the past hour waiting to get in. Isabelle was less than please that they had to wait and was grumbling about not getting there earlier to be closer to the front of the line. The Five of them were debating on leaving and coming back the next night, in hopes the crowd wouldn't be so bad and they could get in earlier by arriving earlier and waiting just as long for the doors to open. Clary rolled her eyes she was getting tired of Isabelle's ranting but she was sure all of them were, her assumptions were proved correct when Jace told her to shut it causing Isabelle to give him a dirty look before the five of them stepped out of line figuring they could find something much better to do than wait in line till most likely closing time.

"Really Jace, you're looking for demons now?"

Alec asked giving his parabatai, a strange look even though he had a good idea what Jace would say in return to him, because that was his way of thinking and they all knew it.

"What, when there is nothing better to do. Find Demons."

Jace remarked to Alec as they walked down the street stopping near the Alley when the sensor went off, and he continued speaking,

"Ah just what we're looking for."

As they headed toward the Alley the scuffling within became evident to their ears and the shadow hunters withdrew their Stele's, Clary holding out the witchlight so they could see. The bright light igniting the alley with a blaze of colors. They could see the fight going on and to their eyes it appeared to be a mundane fighting with three vampires. The three shadow hunters did not speak or form a plan they sprung into action as Clary and Simon hung back, Clary holding the witchlight high to keep the Ally well lit, but by the time the Shadow hunters even grew close to the fight, the blond they believed to be a mundane had slain the vampires and stood, stake in hand only looking away from the dust at those she now realized were in the ally with her.

"How the hell did you - ?"

Alec was the first to speak and Clary and Simon joined the group of shadow hunters as Aderes raised an eyebrow at them,

"You act like you've never seen a girl slay something before."

She said and gave a smirk before turning to grab her bag and leather coat. Ignoring the pain from the cuts scrapes and dug in gravel that covered every inch of uncovered skin, which tonight was a lot as she hadn't planned on slaying, even though as always she came well prepared. But she did not give the group time to speak, nor did she say more. She took up the fire escape and even though Jace and Alec followed when they arrived the roof top was empty. As if she had been a shadow, and hadn't existed.

CLOSING STATEMENT : I hope you enjoyed the first chapter, reviews mean a continuation of this story. so please review / comment and i will surely continue.