So, if I were to say that Sophie's last name was "McGuffin," would that be too much?
Anyway, "psychopomp" was one of the titles of Hermes, the ancient Greek messenger god. One of his jobs was to guide souls from the upper world to the banks of the river Styx. Hermes' counterpart in Roman mythology was Mercury, and that little thing Jolene is carrying instead of her stop sign is based on the astrological symbol for the planet Mercury.
There! I knew that M.A. in Classics would come in handy someday!
One - The Crossing Guard