"It's okay, Ron, I know that I can trust Hermione, I've been working on her all year long, since just before we got off the Express. Don't you remember how she started talking at the end of the conversation? The spell that I used caused feelings of trust in her, and it also caused her to adjust her views on things. I mean, really, do you honestly thing an innocent little muggle girl, no matter what the provocation, would accept my plan for Snape's demise and just tell me to be careful? If she hadn't been accepting my changes, she would have been screaming for an adult, or at the least, trying to make me change my mind. No, Hermione is quite trustworthy, although I don't want to expose her to too much at once. In fact, I think I should talk to Dad about getting her instruction in Occulmency before I let her in on any of our secrets."