Where the Wind Blows
I think that the theme of this book is that even if you are struggling with problems, never give up. The night is the darkest just before dawn. There are kids in the book that are genetically altered to have wings and superhuman traits, and they escape from the school where they were being operated on. They are all changed for life, but they adapt to their new forms and don't give up hope even when they are being hunted by the ones who took them captive in the first place. The setting affects the characters mood, because a lot of where they are is damp and dark areas. This could give them more of a reason to give up, but instead they do not.