This book is told in alternating chapters by twin teens: one girl, one boy, one gay, one straight, both looking for a boyfriend. They're in the center of seven kids in their family, and it's a typically strange kind of normal family.
When there are nine people in the house, what's one more? So the family takes in another teen for the last month of school, so he can finish out the year before moving with his family. He's quiet, artsy, very goth, and says he's a vampire. Both Kyle and Judy are intrigued by this addition to the family - he's their same age and mysterious, both off-putting and also strangely attractive.
Really, this is at heart a teen discovery novel - a bunch of young adults feeling out the edges of their world to figure out where they fit in and who they will become. Nearly everyone's different in one way or another by the end of the book, and while there is some drama involved, it's not a tacky "after-school special" lesson.