I'm going to assume that Darius is somehow related to the nobleman who went after Drake's family.
We still don't know why that was in the first place, of course - they could have been tricksters for all we know.
EDIT: Also, wherever Arae is, sounds like it's a good place to avoid if you're not even allowed to attend your own trial.
Also, Drake does have leverage herself, since she can tell people things Mana doesn't want them to know about that whole zombie headmistress thing she has going.