Fade to Us, by Julia Day

Brooke's summer plans get disrupted when her stepfather announces that his daughter Natalie is coming to live with them for the summer.  Natalie has Asperger's and is a handful to care for.  Among other things, Natalie needs activity so Brooke sets her up with a teen summer drama program in town doing a production of Oklahoma!  But it quickly becomes apparent that Natalie needs help coping during rehearsals and Brooke is the only person in the family who can help.  This forces Brooke to quit her summer job.

Bored in her new role of babysitter, Brooke volunteers to help with the play.  This brings her into close contact with Micah, the stage manager, and the two of them fall in love.  However, Natalie also has an attachment to the boy.  Worried about Natalie will see the relationship as a threat, Brooke insists on hiding the relationship from her stepsister, with predictable disastrous results.

It's a fair story told competently, but without a lot of depth. Day gets the job done, providing good pacing and plenty of plausible interactions, but we don't get much about any of the characters.  Natalie, in particular, who ought to have a lot of interesting layers to her, just comes off as obnoxious.  Brooke, meanwhile, acts like a saint.  Neither is terribly interesting.  Conflicts with the parents are largely resolved superficially or off-camera.  For a story that ought to be about character growth, we frustratingly don't see much under the hood.