Leah was first seen in Stolen, where she appeared to be a fellow captive. It was eventually revealed that she was helping Katzen, a sorcerer and that they were trying to build their own cabal, using humans to gather various supernaturals. She also killed Ruth Winterbourne, and tried to blame it on Savannah Levine.
She was seen again in Dime Store Magic, this time working for the Nast Cabal, who was trying to get custody of Savannah, who was under the care of Paige Winterbourne, Ruth's daughter. Leah was killed by Paige, at the end of the novel. In Waking The Witch she escapes and cons a necromncer to find her a new body, Jesse Aanes. Eve Levine and Jaime Vegas knew she escaped, but didn't tell Savannah so as not to worry her. This turned out to be a mistake as Leah messesd up Savananh's first case and sent Kayla Thompson to foster care while trying to kill her. Jaime sent Leah back to hell with better guards.
Leah is a Volo (telekinetic) half demon. She was born sometime in 1970, and worked as a cop for some time in Wisconsin. Her hair was dark red, and she had green eyes.