Listen by Nancy Cofelt

Brilliant depiction of three separate characters whose lives intertwine.  Kurt lives with his grandmother and his intent in life is to get enough money so he can travel to live with his father.  And he hasn't heard from him in months.  He meets Carrie who appears normal to him when he first meets her. She wants to rescue neglected animals.  A godsend - she will pay him for every neglected animal he brings her.  It appears normal that she talks to her animals, but Kurt doesn't pick up that she hears them talking to her.
Will, a good student, whose brother is in jail, lives by himself. He's dropped all his friends. He becomes Kurt's tutor.
Things gradually unravel for all three.  Kurt brings a dog to Carrie and sees that this dog isn't really neglected and is unhappy at her house. Will dislikes Kurt at first, but then sees him out late at night in a strange location.  He doesn't know if he should get involved.  And Carrie is getting stranger and stranger. Then there's a neglected baby.  And Carrie rescues her.

photo of cover from http://search.barnesandnoble.com/Listen/Nancy-Coffelt/e/9781934813072