The shape of human life
The two stories were originally published independently, but were also sold together under the title The Confusion, which is sometimes controversial, but not without merit. The two stories show two connected narratives about love and adventure. In the first book, we see the human story of positive action and a male personality. Jack is an active and direct threat. In the second book, we see a masterful use of passiveness for the same advantages. Eliza's use of indirect power shows a contrary and opposite experience of life in a feminine mode.
Karma and fate
Thematically, it is hard to see much of the novel without noticing karma and fate. For instance, Jack's story and Eliza's story are both shaped the same way: by struggling to survive while slaves to other people's will, both characters hone skills, competencies, and capacities that allow them to thrive later in life. They both become heroic leaders in communities because of their enormous wealth, but in the story, that happens in stages; they figure out one new thing, and then the book rewards them with a better fate.
Political power and money
The novel also provides a commentary on money and power. Because the stories occur in the distant past, the slaying seems more "normal," because the slaying occurs the context of "pirate" life. But then, in the second book, we see Eliza is also murderous and vengeful, and she is skillful with deceit and sexual power games. Together, Jack and Eliza are depictions for the kinds of people who thrive in power. Those who are willing to kill or deceive tend to be powerful and wealthy in this book, with thematic implication.
