I know this is super old,but I was also looking for this book and I think I finally found it! It’s The Stranger byThe Stranger by Caroline B. Cooney
From the first moment she sees him in class, Nicoletta is drawn to Jethro, fascinated by his dark, mysterious face. She is attracted yet repelled, interested but afraid. Nicoletta becomes obsessed, unable to think of anything but this strange boy.
But she knows so little about him.
Until she follows him to a deserted cave on the edge of town ... and learns the truth.
Jethro is not like the others. No, not at all.
He has a terrifying secret. A secret no one must ever find out.
