In Chinese folk belief, no fox is only an animal for its whole life. Left undisturbed for enough decades, generally reckoned in the hundreds, an ordinary fox is held to accumulate supernatural power, growing the ability to see across great distances, to appear in dreams, and eventually to take human shape, almost always the shape of an alluring young woman. The transformed fox, huli jing, then moves among people rather than around them, and what happens next depends entirely on which story is being told.
The Qing-dynasty scholar Pu Songling collected hundreds of such stories in Liaozhai zhiyi, Strange Tales from a Chinese Studio, and gave the fox spirit its widest and most contradictory literary life. In some tales she seduces a scholar and drains his vitality night by night until he sickens; in others she nurses him through poverty, argues him out of bad decisions, bears him children, and grieves convincingly when the marriage ends. The same collection holds foxes who trick corrupt magistrates and foxes who outwit bandits on a traveller's behalf. No single moral attaches to the huli jing the way one attaches to a Western vampire or a Japanese oni; the fox spirit is dangerous exactly to the degree a particular story needs her to be, and sympathetic exactly as often.
Popular religion absorbed the belief rather than condemning it outright. Small fox shrines and fox-spirit cults, tolerated unevenly by different dynasties and different local officials, treated the huli jing as a being worth placating rather than a myth to be dismissed, evidence that the fox spirit was taken, at street level, considerably more seriously than elite literati commentary always let on.