Content Warning: The section contains depictions of child abuse, drugging and overdose, forced pregnancy, graphic torture, kidnapping, miscarriage, racial slurs, rape, and suicide.

Diana and Matthew initially encountered Jack during their timewalk in Shadow of Night. In The Book of Life, Jack transforms into a vampire when Andrew Hubbard, the vampire king of London, turns the dying 20-year-old before he succumbs to the plague. Jack’s character significantly illustrates Diana and Matthew’s parenting skills while offering an alternate example of how blood rage can manifest.

Jack vividly exemplifies the devastating nature of blood rage. Encouraged by Benjamin Fuchs, the young artist brutally takes the lives of several individuals across Europe. Jack’s blood rage easily triggers in response to a range of emotions, in stark contrast to Matthew’s, which is provoked only by anger. However, Jack also learns to manage his blood rage effectively. Sometimes, his blood rage takes the form of frenzied drawing or music rather than violent impulses. Under Matthew’s guidance, Jack learns to establish boundaries and employ coping mechanisms. By the story’s conclusion, Jack’s blood rage is well-controlled, challenging the Congregation’s belief that all vampires with blood rage must be eradicated.

Additionally, Jack’s character showcases Diana and Matthew’s parental abilities. Diana provides him warmth and comfort, while Matthew offers support and discipline.