The Athrean Obols

Some claim that Athreos doesn’t collect coins out of greed but because he’s looking for five specific treasures. Apocryphal writings in the Underworld library of Oneirrakthys say that Athreos was the first mortal to die. When he came to face the gods, he brought a single treasure as an offering to each of Theros’s five mightiest deities, hoping to receive a peaceful place among them in return.
The gods realized what Athreos’s spirit represented: the first of an endless flood of mortal souls that would soon begin to join Athreos in death. Unwilling to spend eternity sorting the endless stream of dead mortals themselves, the other gods did give Athreos a place among them, as well as charging him with his impossible task. They also offered him a measure of hope. The gods cast Athreos’s offerings back into the mortal world in the form of five coins. They promised Athreos that, once he collected the coins anew, the gods would free the River Guide from his service and welcome him into their ranks. Ever since, Athreos has labored, both at ferrying the dead and in search of his five lost coins, called the Athrean Obols. It’s said that any who bring the River Guide one of the coins will be rewarded with a wish for anything Athreos can grant—even exception from death.