Here's one reviewer's take:

"Originally marketed as "occult horror", Ariel is neither. It's a story of the madness that lies just under the surface, and what it takes to bring it out; the need to give evil a face and a name. Who better to scapegoat for unexplainable tragedies than the one who is Different? Ariel is adopted, and looks slightly unusual. Her unstable mother never fails to assume the worst, almost deliberately misreading the girl's ordinary teenage perceptiveness and need for privacy. By the book's end, almost everyone believes that Ariel is a monster — including Ariel herself.

"Great characterizations, wonderful descriptions — I want to live in Ariel's house. I could wish for a sequel, or just for more books like it."

And here's LB's:

"A publisher provided the premise of Ariel—an adoption that went awry. I was in Charleston when I began the book, and chose that extraordinary city as its setting. I don't know to what extent the book works—I should note that not every reader agreed with the one quoted above—but I greatly enjoyed the interplay of Ariel and her friend Erskine, and on certain nights I can still hear her flute off in the distance."

This Classic Crime Library edition of Ariel includes as a bonus the first chapter from the third book in the series, Grifter's Game.