He tests them

The power he felt having control over his colleagues' lives was intoxicating. Every decision he made was its own cruel pleasure. He watched Caroline's curvy hips bob as she skipped to pick up lunch, her silent obedience a sharp contrast with his booming commands. When Isabelle had to get a parcel, he pretended not to take delight in the sight of her bouncing breasts as she ran up and down the stairs. His favorite though was Claudia - when something fell to the floor, her face contorted with humiliation; his gaze never leaving her as groveled on the ground like a dog.