I’ve seen these deities at temples, but, for some reason, have never given them a second thought until I came across one of them in The Way That Lives in the Heart: Chinese Popular Religion and Spirit Mediums in Penang, Malaysia by Jean DeBenardi [NUS Press].
DeBenardi calls the one in white the Inconstant Uncle, and I have to admit I immediately thought he sounded like something out of a P.G. Wodehouse novel. In fact, the unit name for these underworld lords is Heibai Wuchang (黑白無常): Heibai just mean ‘blackwhite’, while Wuchang is usually translated as ‘impermanence’.
DeBenardi’s ‘Inconstant Uncle”s name is Xiè Bì’ān, while his partner, is Fàn Wújiù (范無救). Their duties include escorting wandering spirits back to the underworld and punishing the sinful.
Xiè Bì’ān is usually portrayed wearing white robes and a tall hat. He is tall and slim, and his tongue extends quite a long way out of his mouth. On his hat is written ‘Get Rich at First Sight’ (一見發財), or ‘Luck at First Sight’ (一見大吉), or ‘You Too” (你也來了). He holds a fan in one hand and a fish-shaped shackle or wooden sign in the other hand.
Fàn Wújiù wears black and is usually portrayed as the darker skinned, shorter, more rotund of the two. On his hat bears the characters ‘World Peace’ (天下太平) or ‘Arresting You’ (正在捉你). One hand holds a fan, while the other holds wooden sign that says “Good and Evil are Separate and Distinct’ (善惡分明) or ‘Reward Good and Punish Evil” (獎善罰惡). A long chain is wrapped around one of his arms.
There are various stories that explain how Xiè and Fan were granted immortality and given their underworld jobs. In one, the pair were constables. One day, when a convict they were escorting escaped, the pair decided to split up to look for him. They agreed that they would meet under a certain bridge, but when the appointed time came, one of them was delayed by heavy rain. However, although it started flooding, the one who was waiting under the bridge refused to budge and was eventually swept away into the river. When the other man finally got there and saw his friend’s body floating away, he was so distraught that he hanged himself. I have read this story on different websites, and there’s no consensus on which man drowned and which one hanged himself. Either way, the Jade Emperor was so impressed by the Xiè and Fan’s loyalty and devotion to one another that he made them guardians of Diyu (地獄), the Daoist underworld.