If enough people were chanting Ember's name, theoretically, she could control Vlad. Although like my friend said, she would probably already be controlling Danny at the time, and Vlad would know something was up. But then, if she wasn't focusing on controlling the masses and just focused her power, it might take substantially less power to control someone as powerful as Vlad.
I'd like to see someone explore this idea. What do you think she'd do with Vlad? I mean, does she know he's a ghost hybrid? I doubt Ember would do many of the things fangirls would do to him (She'd be into guys closer to her age, methinks) but if she had access to his money and power, she'd be unstoppable.
So, um, I thrust this plot idea upon you to do with as you wish! *bestow*