为虎作伥 (Wèi hǔ zuò chāng)
Act as a chang ghost for the tiger—Help a villain do evil
伥Chāng is the ghost of someone devoured by the tiger in ancient Chinese legend. Legend says, the 伥chāng ghost helps the tiger eat other people. The idiom 为虎作伥(Wèi hǔ zuò chāng) has developed from a very old Chinese fable.
Long, long ago, once a tyrannical tiger was out hunting for food in the forest. To his delight, he caught sight of a man. The beast stole near, sprang on the man, killed him and made a nice meal of him. Ferocious and greedy, the tiger didn’t let the soul of his victim go. The soul now had become a ghost which is called the 伥chāng . The beast said he would let the 伥chāng go only after the ghost find him another man to eat. Then the soul of the second man would take his place.
The chāng ghost was most willing to help the tiger. He guided the tiger to another man, and even helped undress the new victim so that the tiger could eat him more easily.
The popularity of this story shows people’s hatred for those who regard the enemy as kith and kin and serve as a jackal for scoundrels and villains.
为虎作伥(Wèi hǔ zuò chāng) is close to the English saying “To hold a candle to the devil”.