Matchstick wrote:
I have to say, I'd be pretty tempted to have the influential person be a bad guy. Greedy, self interested, or even an agent of the Enemy, hiding behind a smiling facade. The characters then get assigned small good deeds, but progress to larger questionable deeds. Eventually, they have to decide whether to keep doing these things, to betray the sponsor somehow, or something in between.

That would be a great way to use Saruman in a Rohan minicampaign. Something similar to how Arciryas (from HotW) is described.
He could be a Patron of the characters, giving them hints and leads to disrupt plots from the Enemy, but also asking to bring back certain tokens and items to him in Orthanc. Until the quests tend to be more centered in recovering the objects of Dark Lore than in disrupting the plots themselves and the company begin to suspect what are the true motivations of the White Wizard.
And then, one day, a hero discovers that one of those objects is a book called Necronomicon...