Cycler by Lauren McLaughlin

While extremely far-fetched in its premise, this is an interesting look at gender and gender identity, and one of the rare books for teens dealing with bisexual characters.

Every month, for four days, Jill's alter-ego Jack comes to the fore, complete with teenage male body and desires. Jill has learned to block out all memories of these takeover of her body, and until this year Jack has agreed to stay hidden at home. But now he has a crush on her best friend, and even window bars and a keypad lock system on the door can't keep him inside. Meanwhile Jill has a crush of her own, on bisexual Tommy. What happens when both Jack and Jill are on the loose on the same night makes for an interesting conclusion.

The subplot of her parents marital problems is not explored and should have been left out, but otherwise this is an interesting and, at times, funny book.

*** Of interest

Random House, 2008     ISBN  0375851917