As stated above, Mist was born Misty Greycastle, the younger sister of Lander Greycastle, the current lord of Greycastle. All of the Greycastles are lycanthropes of one kind or another, but Misty was special because her shapeshifted form was that of a 'silver wolf'--a form which the priestess of Selune said marked her as a favored one of the goddess of the moon. She was stolen from her home on Midsummers' Eve when she was six years old by the Malarites of the Wildwood. Though her family searched long and hard for her, they eventually had to give her up for dead, thinking the Malarites must have killed her.
In reality, the Malarites sold Misty to the Aurilites, having no wish to hunt a child. She was raised in an Aurilite community far to the North, and when she reached adulthood, distinguished herself as especially cunning and skilled in espionage. As a result, she climbed in the ranks of the Aurilites, eventually becoming all but head of the Aurilite spy network in the Karen Valley. She could boast that her spies were better than the Ferrets, since they evaded the agents of Beldin so effectively. Because of her silver wolf form, she was called the White Wolf, and so became known to the people of Beldin.
During the first part of the Fourth Winter War, Mist stayed near Astrid Rock. Her favorite hunting and roaming land was the Aelfwood. Her influence was felt down in the lower valley through agents such as the Shadow.
When Beldin laid siege to Astrid Rock, White Wolf made a bet with Ronin Eininfar that Beldin could not defend Karenlynn from 'her' army. If the Aurilites took Karenlynn in the next great attack, according to the wager, Ronin would surrender himself as their prisoner. If the Aurilites failed, White Wolf would surrender herself to Beldin. He took her up on this bet. The Aurilites attacked Karenlynn with some of their strongest forces, and in the middle of the battle a great white wyrm landed in the city. Despite terrible odds, the defenders beat off the attack and killed the dragon, but at the moment of victory, being completely exhausted from the battle, were overcome by a small desperate band of Aurilites. Ronin Eininfar was taken captive by the Aurilites, though he was rescued a tenday or so later.
White Wolf's motivation in making the bet was partially her own sense of 'fun', and partially a hatred for being second in command to Brinja Jotunsdotr, the head of the Aurilite Fangs and Claws. She felt that Brinja knew nothing about organizing an effective spy network, and so felt a certain injustice. So when she was apprehended in the Aelfwood a month or so later, again by Ronin Eininfar, she surrendered upon being defeated. He took her swords, Gael and Blizzard, and she was returned to her family, where she remained under house arrest. To spite Brinja, she gave up the names of all the Aurilite spies in the valley soon after, effectively destroying the network she had built.
Mist remained under arrest with the Greycastles for some years, before being pardoned and allowed to join the Bounders. Even though, given her experience, Ferrets was more in her line of work, the Ferrets would not have her, and she still held them in disdain. When Keyna resigned from the bounders in 1391, Mist was one of the most eligible candidates ability-wise for the post, but was passed over due to her past. That does not keep her from helping her nephew, Wulf, at his post as head of the bounders, making her effectively the second in command of the Beldin Bounders.