The book The Face on the Milk Carton is a man vs. self story. Janie has to try and figure out who her real parents are for herself. Janie is forced to decide if she wants to live with her fake parents who have raised her for almost her whole life, or with her biological parents who actually gave birth to her. Imagine the struggle, having to choose between the parents you’ve been with your whole life and your biological parents who you were separated from at birth. This book is a man vs. self story.
In the book Twins, the message is to not judge a book by its cover. The reason for this is because Mary Lee thinks that Madrigal, her sister, has a super good life because she’s happy and all smiles on the outside but on the inside she is very rude and a murderer, for example, her mother mother had said that Madrigal was out to get Mary- Lee so luckily nothing happened. This is a very good lesson to teach people how not everyone is how they seem on the outside.
Another lesson is not always trust the one the reader loves the most. For example, Mary Lee trusted her sister very much and loved her in every way possible, but Madrigal was actually out to kill Mary Lee. For example, The parents had told her that they suspected Madrigal was planning for the death of her sister but they had sent Mary-Lee to school before anything could happen. So Caroline B. Cooney wants people to also know that one can’t always trust the people that one may love the most.