Just having read through Chapter 2 I could definitely see Dumbledore bringing Hermione into this to try to cause trouble for Harry. Also, in order to throw some variety into the types of Natures Harry has to deal with, and as a way to eventually bring her into the fold, you could have Hermione be some kind of Combative/Dominating Submissive. While it's in her Nature to submit, her Nature (read canon personality) won't allow it until that person proves themselves equal to her physically, magically, argumentatively, etc. or any aspect of the above.
That's not to say that this dominance is permanent though (even though the relationship might be). It's only once the emotional battle's engaged that Hermione would start revving up. Should someone get the better of her she'd love nothing more than to be fucked by them in all their glory. Should she win though, she'd fuck him and fuck him hard so that they'd know who won the fight. After that they'd go back to normal/relationshippy normal until the next fight.
Being a Master of slaves is one thing, but eventually having no spirit in those he's Dominating would make it one long boring endeavor.