In The Brothers Hawthorne, there are four key families: the Hawthornes, Blakes, Graysons, and Johnstone-Jamesons, with crossovers between them. Jennifer Lynn Barnes, through these four families, explores the different ways family loyalty is cultivated and the outcomes of that loyalty, both in biological and found families. 

In biological families, there can be an expectation of loyalty; Barnes demonstrates ways that expectation is upheld and discarded through Sheffield Grayson’s relationships with Grayson and Colin, and through Jameson’s relationship with the two sides of his family tree. In the first three books, Sheffield Grayson’s reason for attacking Avery Grambs is that he believes her to be the biological daughter of Toby Hawthorne, whom he blames for his nephew Colin’s death. He continues to bring Colin’s mom, Kim Wright, money after Colin’s death to help her, but he doesn’t introduce her to his twin daughters. Savannah sums up the difference between Sheffield’s loyalty to Colin and his relationship with his other children: “Our dad loved Colin. Maybe he loved us, too, but we weren’t Colin” (302). Grayson notes that the only time Sheffield refers to him as his son is in the secret journal, the day he kissed Avery: “Toby Hawthorne’s daughter, he’d written, doesn’t get to kiss my son [.