Consider the main character: what does he or she believe in? He believes in survival. He will fight for his family and I liked the strength he displayed.
What are the most important relationships in the book? The relationship between Dan - Mary - Annah - Laura.
What makes a minor character memorable? It would have to be Dan, I guess. The author went to great lengths to make sure you would think of him even after you finished reading the book.
Disclosure: I received a review copy of this book from the author.