Hero - Jim Ellison and Blair Sandburg share the Heroic function in this show, with each of them pursuing separate, but usually parallel Quests.

Mentor - Simon Banks is cast as the primary Mentor for the physical Quests, the usual role of the "Captain" in police shows. Incacha was clearly the Sentinel's first Mentor, and Blair Sandburg Mentors both Detective Ellison and Sentinel Ellison, who sometimes have very different needs.

Both Simon Banks and Ellison Mentor Blair as he pursues the Quest to be of service to the Sentinel, which means learning to live and function inside of the police community.

Herald - It's the re-awakening of Ellison's senses that draws Blair into his life, and Herald Sandburg delivers the Call to Action by challenging Ellison to learn to control and use his heightened senses. As frequently happens, the Hero Ellison first refuses the Call, then later accepts it.

Similarly, the Herald for Blair is Jim Ellison. The appearance of a Sentinel is Blair's Call to Action. His challenge is to face up to his dream and…do what with it? Suddenly Blair's vague, academic notion of a Sentinel has assumed flesh-and-blood. It's a real person with needs outside of providing dissertation material for a student and Blair coming to terms with this is his journey to maturity.

Shadow - Physically, Ellison is Shadowed by such characters as Alex Barnes, Yuri (whom Sandburg described as a "technology Sentinel"), and other, lesser criminals. Emotionally, Ellison is Shadowed by his father who was everything Ellison did not want to become. Ellison is also emotionally Shadowed by Sandburg's dissertation and the threat of exposure.

Physically, Sandburg is Shadowed by the same enemies that Ellison has. His involvement with the Sentinel project that was his Call to Action drew him into physical danger. Emotionally, Sandburg is Shadowed by the conflict between his counter-culture upbringing and his role, increasingly important to him, as Ellison's partner. The same Shadow of the dissertation that hangs over Ellison, hangs over Sandburg, since the publication of this document will mean the end of Sandburg's partnership with Ellison.

Shapeshifter - Gustavo Rivera and Alan Archer (Dead End on Blank Street) appear as Ally? / Enemy? Shapeshifters. In terms of the anima function, Alex Barnes is the femme fatale Shapeshifter that causes Ellison the most problems. Possibly because of his mother's absence as he was growing up, Ellison seems to have a damaged vision of his anima.

Trickster - Blair Sandburg functions as a trickster in terms of bringing comic relief and challenging the status quo. Naomi Sandburg frequently does the same thing, as do other minor characters. (I loved Sneaks, the snitch. With or without the comedic role, police "snitches" often function as Tricksters in police shows.)

Threshold Guardian - Lash, Kincaid, Lee Brackett, Lila, assorted criminals. Each of these presents a unique problem for Detective Ellison, as well as for Sentinel Ellison, and he must learn to cope with the challenges they offer in order to pursue his Quest (i.e., learn to fully control and integrate his senses).

Sandburg's Threshold Guardians tend to be less physical. They're portrayed by the challenges he faces in learning to help the Sentinel control and use his senses. This is the application of Sandburg's study and research. He takes risks that affect both of them, learns, and grows in knowledge.