"Simple," Harry seethed. "Complete control. If she couldn’t heal, she couldn’t escape. And if she didn’t have the will to escape, she’d lose all will for resistance, too. It’s about utter dominance, pure and simple. You must have sensed how powerful Hermione is ... despite all that she's endured, she still carries around a ridiculous level of magical potency. Even I'm amazed by it ... but I genuinely think she's forgotten her own strength."