Narcissa wasn’t entirely clear on the complex magic behind keying a small addictive dose of potion every time a Death Eater uttered the words "Good Girl’ in the presence of the prisoner, but she could grasp the immediate impact of the dopamine hit to her student. The dopey bliss was clear in the slackening of the captive’s features as she received her first tantalising taste of drugged pleasure. She’d test how far operant conditioning would take her in shaping the subject, she knew that a few rounds of positive reinforcement, would make any subsequent punishment seem all the harsher. She wondered idly what corrective would be triggered if she decided to use the chastening words of "Bad Girl’.