As a nymph, Fei was never supposed to live for as long as a deity. But she made a deal with Ares, the greek God of war so that she could be free to live for a very long time and roam the explored and unexplored lands. In exchange she had to ensure that people will continue to pray to Ares which also meant she had to encourage people to go to war.
As time passed, people have lost their belief in the ancient gods and Ares slowly faded away, as did most deities. Fei was free to do whatever she wanted but she kept her word and worked as a scholar who would gather information during times of war.
Unfortunately, because of certain circumstances she was punished by the eastern gods to live in seclusion in the mountains and never be able to lie to a human ever again.
Now,in the 21st century, Fei resides in the city and has an antique library that also works as a gateway towards the Underworld. She is still punished and still has to work for the remaining eastern deities as gate keeper (she literally keeps the account of who enters and leaves the Afterlife.)
But faces from the past come back to haunt her, especially one that disappointed her and brought the punishment onto her.