** spoiler alert ** 
 I did not expect this story to end the way it did. AT ALL. I literally gasped aloud and shouted "oh my god, what!" It completely fits. And maybe I'm just not suspicious enough because I'd even remarked to myself about how weird it was that the twins never spoke to each other directly in the story. Isn't that the hallmark of the split-personality device? 
 But it was just perfectly done, and perfectly concealed. So much other stuff going on to distract from the suspicions, really. 
 I loved the form, as usual. I especially enjoyed the mirroring of the twins' sections. There was so much done with the "mirror-image" idea: one twin binged, the other purged; one twin froze men out, the other slutted around. But I liked, too, that these splits weren't absolute. We saw Raeanne eating lots of ice cream at one point, and we saw Kaeleigh popping pills and drinking in the last half of the book. 
 I did get confused a bunch of times about the logistics of things -- did the girls have their own rooms? Did they often sleep in the same room regardless? And the switching viewpoints confused me because it didn't seem like the timeline always matched up. Of course, at the end with Ian's big reveal. 
 Such a rich and sad story. Such a great book.