Here's another unnamed character who seems to be here pretty much to teach a lesson: don't make snap judgments based on appearances. Jack mistakes him for a Hells Angel, which isn't too surprising: he's huge, and "had a long beard combed down the middle and pulled back over his shoulders and tied together in a knot behind his neck" (20.2). Oh, yeah, and he rides a chopper.
We soon find out that he actually used to be a Hells Angel, but got tired of "fighting all the time and being really drunk" (20.8). So, now he "just takes care of animals" (20.8). His work is careful and gentle, and he gives War Chief a nice bunch of carrots when he is finished.
He's also gentle with Jack. Here's what he does when he thinks Jack is suffering from heat exhaustion: "He looked me in the eye then reached forward and placed his big, soft hand on my forehead" (20.16). Lesson learned: even scary-looking biker dudes can have hearts of gold.