The suggestion is that Billy, through his experience with the wolf in the wilds of northern Mexico, has somehow transgressed beyond the realm of civilization into some atavistic state. The theme of transgression will be later reinforced when the ragged Billy returns to America (‘Something in off the wild mesas, something out of the past… In that outlandish figure they beheld what they most envied and what they most reviled. If their hearts went out to him it was yet true that for very small cause they might also have killed him.’ [p.170])
In Greek mythology, Prometheus was a Titan and a champion of mankind who stole fire from Zeus and gave it to mortals. Various myths concerning Orpheus attribute the legendary musician as having gifted mankind medicine, writing, agriculture, as well as revealing the mystery rites, often in defiance of the gods.
Closer to the novel’s setting, the two most prominent aspects of the Promethean myth – the creation of man from clay and the theft of fire – have parallels within Mayan and Native American belief systems.