Monster Under the Bed: Fantasy/Horror?

The monster lived under her bed, hiding in the dark shadows cast by the wrought-iron headboard, sliding between the bars while she slept and whispering sticky lullabies in her ears. She knew the monster lived under her bed because Great-Uncle Leroy had put it there when she was a little girl and having nightmares all the time. "You see," he told her, "I'm putting a monster under your bed. He's a very mean beast, but he will do what I ask him to, and that is to chase away all the other monsters or nightmares that might threaten you. All you have to do is prick your finger every Saturday, and let a single drop of blood fall to lie in the shadows. If you do this, he will be loyal to you as long as you live." He added, "And don't tell your mother. One day she forgot to feed her monster, and he left after nearly killing her. She's had--"

Inspiration: The title of "How to Write Tales of Horror..." and I may have been thinking a bit of Ray Bradbury's "The Gathering" once I started.
Story Potential: High.
Notes: Neat. Nifty. I've got no idea where it's going, but I like the idea of a little girl with a tame monster under her bed.