The conflict between family and emotion
A powerful theme in Dark Sons is the conflict between family and emotion. In the novel, Sam's father - after leaving Sam and Sam's mother to marry another woman - has a child with the woman. After his father abandons him and has this child, Sam is put into a strange position and begins to feel strangely. To that end, Sam must determine a number of things, including if he should forgive his father, if he ought to accept the new baby (even though he thinks that the new baby replaced him), and how he can move past his father's transgressions.
Forgiveness
A common theme in Dark Sons is forgiveness. After Sam's father leaves him, marries a new woman, and has a child with that woman, Sam is destroyed by his father's betrayal. With this betrayal in mind, Sam must decide if he will forgive his father for his transgressions. Even if he wants to, can he forgive his father? Should he even forgive him?
Parallelism between past and present
An important theme in the book is the parallelism between past and present. Specifically, Grimes' novel parallels Sam's story with the story of Ishmael, the son of Abraham, as outlined in the Book of Genesis. Like Ishmael, Sam must contend with and deal with the emotions related to his family having another child (one who presumably replaced him).
Conflict between father and son
An incredibly important theme in the novel is the conflict between father and son. In the novel, Sam frequently thinks about his father, who left and betrayed him. He is in almost constant conflict with his father, whom he oftentimes feels negatively about. He also has a tremendous amount of internal conflict about his father and his actions. Specifically, Sam wants to know how he fits in with his father's actions.
