As Simple as It Seems by Sarah Weeks

Verbena Colter knows she's bad news.

Trouble from the get-go. How could she not be, with parents like hers? Her mother practically pickled her before she was even born, leaving Verbie to struggle with the effects of fetal alcohol syndrome. And her father was just plain mean. Verbie wishes she could be somebody, anybody other than who she is. Enter Pooch, a flatlander boy visiting for the summer. When Pooch and his mom rent the house next door, Verbie takes the opportunity to be someone else entirely. And what starts out as a game leads Verbie into a surprising and heartwarming journey of self-discovery.

Another gem from the author of So B. It.