Cassie's mother smiled as as she walked by her daughter's room. Her door was closed, as always, but she knew that her daughter was probably just studying for yet another test. She was proud to have such an intelligent and studious child, a daughter whose grades set her near the top of her class. Sure, she liked her privacy, but what teenager didn't? Cassie's mother still fondly remembered her own teenage days, filled with all sorts of illicit activities caused by a rebellious streak that her daughter seemed to have mostly avoided.
Her smile disappeared as she heard her daughter's voice leaking out from the cracks in the wooden door.
"So, then you can cancel that out from both sides of the equation, right?"
Cassie's mother froze as she listened to her daughter's words. She tried to reassure herself that it was just her going over the material out loud, working through it with spoken words as well as written ones, but the sinking feeling in her gut made her wonder if there was something far worse going on.
Her suspicions were confirmed when she heard a lower-pitched voice speaking in response.
"No, not this time- that'd be dividing by zero, and that can give you all sorts of nonsense answers."
"Oh yeah."
Her mother rapped on the door, gently at first, but increasing in strength with every knock. "Cassie, what's going on in there?"
"Nothing, Mom! Just studying for a math quiz!"
"Who are you talking to?"
"Nobody! I'm just thinking out loud! Everything's fine, alright? Just leave me alone for a bit!" Her daughter's voice was loud and panicked.
Cassie's mother grasped the metal doorknob firmly and eased the door open, grateful that she had not installed a lock for her daughter's bedroom.
Her blood ran cold as she took in the scene before her.
There was a boy in the room. A boy who looked a little older than her daughter, a little taller, wearing dark clothes, the two facing the other way as they bent over a math textbook.
Maybe her daughter had inherited that rebellious streak after all.
"Cassie?" she asked cautiously. "Who is this?"
Cassie turned around and stood up, her eyes full of fire. "Mom, I told you to leave me alone in here! You can't just come barging in here like this!"
"Cassie, why is there a strange boy in your bedroom?"
The boy stood up and faced her.
…no, not a boy. No normal boy would have eyes of yellow and black, or teeth as sharp as fangs. This was something far stranger, far worse than she had imagined.
The… whatever it was took a few steps forward and extended its- his?- hand, giving a wide grin that further displayed his too-sharp teeth.
"You must be Cassie's mother! I'm Alcor, I help your daughter with your math homework. It's nice to finally meet you."
Cassie's mother stared at the claws on Alcor's extended hand, unwilling to reciprocate the gesture or to meet his dark stare.
Cassie gave her mother a sheepish grin. "…I can explain."