The premise of the book is an interview with the Devil, where he admits that he dwells in idle minds, and finds it easy to control the minds of drifters.
The separate throttle is split to control both engines individually, and offers detents that tell you when you're about to idle the engines and when you're about to light the afterburner (which can be removed if you're in a non-afterburning jet -- like indeed the A-10C is).