I got this fair-condition softcover from the local library's ongoing book sale. Written for ages 9 and up, it looks pretty darned creepy!
Later: Good story, a changeling tale from the viewpoint of an elf-child, Tom, who's not a perfect specimen of his kind and is becoming aware that the others are planning to deal with him. These elves are feral, mostly solitary, blood-loving meat-eaters who are wildly, joyfully savage - and the story does a good job of depicting all this from the protagonist's viewpoint as he goes through the struggles of juggling his preferred nature with his desire to survive.
The "demons" - mortal humans - are shown in interesting fashion too, at first from Tom's wild-elf viewpoint and gradually as more sympathetic, as Tom begins to realize how different they are, and how the "enslavement" of emotional ties can be a positive thing.
The plot winds nicely, with a somewhat predictable revelation about the nosy neighbor-lady that still fit in with the tale. (The hints, mostly centered on the song "The Ballad of Tam Lin", pretty much tipped me off as to what was going on right away, but I did like the unfolding of the truth from the characters' perspective.)
Definitely bittersweet, and often quite scary - good story!