Thrall

A thrall is a human person put under some kind of mental control.

Description
In Summer Knight, Elaine Mallory describes what it was like. She didn't know it was happening at the time. She didn't have the ability to think clearly. Justin told her that he just needed her to hold Harry down long enough so he could explain things to him and everything would work out. Justin used her trust of him against her.

They are divided into rough thralls, whose free will is completely removed and essentially behave like machines, and fine thralls, which may not know they're enthralled. It takes a subtle hand, a lot of time and a certain amount of empathy—sort of like what Justin DuMorne did to Elaine Mallory. They may be freed or recover over time, unlike Renfields.

Making a Thrall is against the Seven Laws of Magic: "Thou shalt not enthrall another".

Summer Knight
In Summer Knight, Harry Dresden and Elaine Mallory discuss their past with Justin DuMorne. Justin had already made Elaine his thrall, then commanded Elaine to pin Harry down while he tried to invade Harry's mind to enthrall him.

Blood Rites
Mavra has made a nest with her scourge under a homeless shelter through Undertown. She has made rough thralls of some of the shelter's staff to cover for them.

Lara Raith makes a thrall out of her father, Lord Raith, the White Court King, making her the ruler behind the throne.

White Night
In White Night, Harry Dresden and Carlos Ramirez are escorted by Lara Raith down a red carpeted pathway leading to the Deeps. Along the path are human thralls, kneeling, draped in white silk kimonos and tied with a single strand of white silk around the throat to poles. These thralls are intended to be "food" offerings to the guests of an impending White Court meeting of the different houses. Along the path with the human thralls were small Faeries in cages forced to be lights for the path.