Symbolism, Imagery, Allegory
Finally, we should mention that Krauss has actually chosen symbols for each character. The chapter titles are accompanied by a symbol corresponding to the main character in that section. Leo has a heart (like, a real heart, not a Valentine heart), Alma has a compass, Litvinoff has a book (guess which one), and Bird has an ark. You can read about what these might mean over in our "Themes" section.