Narcissa could see the muggle-born was focusing her saucer-like eyes on the small tin of tablets, she purposely repeated herself driving home her previous instructions, this time she added the final tidbit of information, that Hermione would be expected to listen to her slutty body. She could tell that Hermione wasn’t really absorbing the lesson. The prisoner was jonesing for her next hit, this only served as the opportunity to allow Narcissa to turn on the slave’s "hearing aids’, with the captive oblivious to this use of covert magic on her body.