Jantzen Hefferly's true nature is disguised in much of Book 1.

Jantzen was the second subject to be modified through the human-hybrid project. He appears perfectly normal, with a narrow face, black hair, and a tight beard. An observant person might notice that his eyes glitter with a hint of purple.

Jantzen has been hybridized with a squid and can dematerialize into purple smoke. His eye color turned purple in his transformation, and the purple becomes stronger just before he dematerializes.

Jantzen was Rodheimer's childhood friend and is the true genius behind the human-hybrid project. As teens, he developed a crush on his friend. Unable to tell him, he became his most ardent supporter in the research field after Weston Rodheimer's wife, Meg, died.

After being at Rodheimer's side for the six months when Rodheimer hovered at life and death during his transformation, Jantzen begged to be the Project’s second trial subject. When the Project shifted from benefitting mankind to benefitting the military, Jantzen's love for his teenage crush slipped into hate, and his goal became to bring Rodheimer and his human-hybrid project down.

When Garik Shayk is captured and impressed into the human-hybrid project, Hefferly bonds with him as an ally and becomes his mentor in all things hybrid.

We first meet Jantzen in Book 1 of The Human-Hybrid Project, Shattered by Glass.