Zhang, Kat. 
WHAT'S LEFT OF ME
New York : Harper, 2012
IL YA
ISBN 0062114875

In a world where everyone is born with two souls, Addie and Eva are different.  As a child grows, the dominant soul takes over and the weaker soul fades away into nothing.  Despite being weaker, Eva is still hanging on.  While she can no longer move or communicate with anyone but Addie, she's still alive.  But in America, keeping both souls, being a hybrid is illegal.  When the girls find a possible way to let Eva reemerge, they risk imprisonment or worse.  But to speak, move, smile again, Eva is willing to do whatever it takes...
  (Isinglass Teen Award Committee, 2015)