I expected a lot from this book, and sadly I ended up a little disappointed. 
 The concept is very interesting: everybody is born with two souls that share control of the body, but at a certain age the dominant soul settles and the other soul fades. Only that some people don't settle, they are called hybrids and are illegal. Abbie and Eva did not settle and have to keep this secret... 
 Despite the awesome premise the book did not quite work for me, I just felt like Abbie/Eva were really immature and I couldn't really connect with the characters, also it was a really slow read and could get very confusing at times with the 'soul switches'