This is a short story I thought of based on the Evanescence song 'Haunted'. It's complete AU, so Sebastian and Clary aren't related.
Full description: Clary has been trapped inside a mysterious abandoned mansion for 10 years. She has been trapped there by a mysterious figure who she only sees glimpses of. She makes it her mission to find this shadow and kill it, so she can be free. But with this stranger being her only love and her only hate for so long, will she want her freedom when it is presented to her?
The sun was just beginning to set, dying a sky a bright orange. The air was still and calm, as if it were waiting for something to happen. Clary came skipping down the street, bouncing a ball as she went. Giggling, without a care in the world, she watched as the ball bounced up and down, making the most of her time outside before she had to go back home. She hated her home. Her father was always angry, and her mother was always distant. They didn't think their six year old daughter heard their arguments in the middle of the night, but she was always wide awake, crying as she heard her parents scream about how much they hated each other.
Reaching the end of the road, Clary looked up at the old Morgenstern Manor, a once proud building now falling apart. She had heard many stories of eerie disturbances on the grounds, ghostly figures and strange disappearances. Clary had always been scared of the mansion, but fascinated at the same time. Lost in her thought, Clary didn't notice that she was bouncing her ball dangerously close to a fallen branch, and when the ball hit the branch it ricocheted off and flew towards the derilect manor, straight to the wide open door. Knowing her father would be angry if she lost another one of her toys, Clary plucked up her courage and ran after her ball. The ball picked up unusual momentum, and flew straight through the open door, stopping Clary in her tracks.
She looked up at the house, which now seemed to be watching her. It was dark and ominous, giving off a strange aura of dread. Clary did not want to go in there, but she knew she had to get her ball back. So, taking a deep breath, she walked up the steps to the front door and walked inside. Clary could barely see an inch in front of her, despite the fact the door was open. The floor was covered in brown leaves and bits of broken wood, showing how long the manor had been abandoned for. Despite it's ghastly appearance, Clary could see the grandeur this place once held. Pieces of artwork with broken frames littered the hallways, and the crystal chandelier was still hung up, though it was falling to pieces. What Clary wouldn't give to live in a house as big as this one day. The exquisite details, the grand swirling staircase, this place could look like a palace.
Suddenly, a loud groaning noise distracted Clary from her daydream, and she yelped in surprise. Forgetting about her ball, she turned to run out of the front door, but to her shock, the door had vanished, and in its place was a blank wall. The entire house was pitch black now, and Clary was shaking with fear. She had to find a way out. Grabbing the skirts of her dress in between her fingers, she ran through the house, desperately searching for a way out. But with every turn she took down another dark hallway, she found herself becoming more and more lost, as if the house was changing its layout so she couldn't find the exit. Gradually becoming more and more afraid, tears began leaking down Clary's face. Why couldn't she get out of here?!
After what seemed like hours of running, Clary collapsed into a corner, put her face in her hands, and began to sob. She was terrified and confused beyond belief. Hopefully someone would notice she was missing and come looking for her. But if she couldn't get out, could anyone get in? What was going to happen to her?