[@Flagg] My honest thought is to play a person involved in some level of that conspiracy. If there are border march kingdoms and other parts of the Empire that feel a certain way, it might be fun to be the agent that dissolves some of those bonds and weakens the whole. 

With a claim + subversion, there's way more opportunity to make the current leadership look bad while steadily working toward building up a base. Keeping the Empire too involved within itself to pay attention outside would be a huge part of that strategy.

Keeping in with the 'magic is mysterious' line of thinking, maybe some of this subversion is assisted with magic. The trade with foul entities for secrets that can be used to blackmail and subvert, the occasional mysterious and gory death in the darkness. Things that are hinted at rather than having a dragon rip off a tower or something.