Synospis :

I should not exist. But I do.

Eva and Addie started out the same way as everyone else—two souls woven together in one body, taking turns controlling their movements as they learned how to walk, how to sing, how to dance. But as they grew, so did the worried whispers. Why aren’t they settling? Why isn’t one of them fading? The doctors ran tests, the neighbors shied away, and their parents begged for more time. Finally Addie was pronounced healthy and Eva was declared gone. Except, she wasn’t . . .
For the past three years, Eva has clung to the remnants of her life. Only Addie knows she’s still there, trapped inside their body. Then one day, they discover there may be a way for Eva to move again. The risks are unimaginable-hybrids are considered a threat to society, so if they are caught, Addie and Eva will be locked away with the others. And yet . . . for a chance to smile, to twirl, to speak, Eva will do anything.

My review :

All the human have two souls, when they are young one of the souls disappears, generally it is the dominant which stays. 

In the case of Addie and Eva, none disappeared even if Eva became weak. She is always present and speaks with Addie every day. They are two inside the same body.

The people as them are Hybrids and they are pursued to be locked and looked.

When Addie and Eva meets Hallie and Devon, everything falls over.

It is a very nice and original story, we have difficulty to imagining  the conflict between both souls. They are actually as twin sisters but they do not want the same things or have the same character. And then Eva was in full ownership of her body until her 13 years. Thus must be complicated enough to be relegated in the background.

I like Eva very much and more we move forward in the book more I wonder why is it her the recessive soul because Addie is afraid of everything. It can be because Addie  has something to lose while Eva has almost lost everything already.
I appreciated the character of Hallie as well as Ryan.

I shall see what it is going to happen in the 2nd volume which is in my PAL and I’ll reading it soon.