How to Set Up Factions So They Can Be Toppled

I've been waffling on the intro to this post for a while. In the interest of ever actually getting it onto the blog, I'll hit you with a couple of bullet points about yourself: You are the dunga master for a group of dunga and darga or similar.You want a recurring enemy faction in the game. After all, recurring motifs are one of the fundamental principles of worldbuilding, arguably the most fundamental (though this is a topic for a different essay).You are unsatisfied with the standard fiver approach to "factions". A couple of scripted fights and the big bad getting away each time until they finally catch up to have a big scripted fight? What happens if the party kills him early, does his cult just collapse? Is the whole adventure over right there?You have come to me now, in desperation. "Help me, Michael," you're saying. "You're my only hope..." Your eyelids flutter. You lean in for a kiss... "I'll do anything you say, Michael" you're contractually obliging. Assuming that you agree…