Find one word that describes a character in your book very well. Collectively, each story focused on a single main character within an unfolding plot. If I had to pick a word to describe these main characters, I would say "tormented". No information is offered about their past but I am very sure they did not end up the way they did without any help from their circumstances or people around them.
Compare two of the characters in this book. Clare and Carl. They both seemed to have multiple personalities and misled people around them. One personality was sweet, nice and approachable and then you had the opposite, which was resulted in bloody endings for both stories.
What part would you change in the story? The stories are perfect. What I would change it page breaks. There are no page breaks and each story / section is divided by a header but this is sometimes misleading because sometimes this header means a continuation of one story and other times it means you are reading a new story.
Disclosure: I received a review copy of this book from the author.