Maybe this time.

A sly smirk curled its way over his face as he watched her through the window. She was making dinner; the window was slightly ajar, enough for the smell of the meat cooking to waft out toward him. He breathed deep, the smell of roast lamb making him hungry, but it was not food he would need to quench that hunger.

He already had his knife in his hand, as he shifted his position the blade caught the last rays of the setting sun and reflected them onto the back porch of the house. Every kill was different for him, every single one, while he stood there he was savouring the moment, planning everything down to the minute detail. He knew he would reflect back on the kill after it was done, wonder about ways to perfect his work, ways to make the excitement of it last longer.
The first kill felt the best, it was sloppy and he was terrified after, but the rush of adrenaline that came with it was like nothing he had ever known before. Each kill that followed it seemed to lose something; they shadowed it in time and in satisfaction. For that reason he had to keep killing, to find that rush again, to work out what he was doing wrong now that he didn’t do that first time.
As he watched her he thought, “This time. Maybe this one will be the one.”
He waited until she had sat down to eat. He knew she was alone, he had watched the house all day. He walked up to the slightly open window in the kitchen. He opened it properly and climbed inside.
He did not attack her straight away; instead he walked up the stairs and intentionally made a sound. He waited, he knew she would hear it, try to ignore it, pretend it was the wind or something. After a little while he made one of the upstairs doors slowly creak shut then he moved far away from it, knowing she would have to investigate.

Sure enough up the stairs she came turning on every light she passed and trying not to appear afraid. He remained hidden, letting her check the room and confirm that it was empty, he even heard her mutter something about it being, ‘just the wind.’
He allowed her enough time to settle down to her dinner again before he made another sound, this time in the upstairs bathroom. He dropped something breakable into the sink, smirked at himself in the mirror above it and then went back into hiding.
She came up the stairs again, her eyes wide and her hands shaking slightly, but still she tried desperately to show no fear. She got to the bathroom, looked at herself in the mirror, saw that she was frightened and tried to calm herself. She looked down into the sink, she smiled thinking herself a fool to be afraid of the sound of something slipping into the sink and breaking.
She looked back up at the mirror still smiling, but it was in that instant that the smile was wiped from her face and she stared in sheer terror at what was reflected in the mirror. He stood right behind her, the blade of his knife shining in his hand. She did not have time to turn around or scream. In less than a second he had moved and slid that blade gracefully across her throat.
She did not die instantly; he held her upright with his other hand as he stared at her in the mirror, blood dripping down from her neck. She couldn’t scream, she couldn’t move, she could feel herself dying and she could do nothing to stop it. Nothing but stare at his reflection in the mirror as it stared back at her.
When she was dead he let her lifeless body fall to the floor.
“Maybe next time. Next time will be the one.”