Monsters of Men by Patrick Ness

As a world-ending war surges to life around them, Todd and Viola face unspeakably vast consequences of each action, each word, each monstrous decision. The indigenous Spackle are mobilizing to avenge their murdered kin, ruthless human leaders are defending their factions, and a convoy of new settlers is approaching. All the while, the ceaseless Noise continues laying all thoughts bare—and the projected will of the few threatens to overwhelm the desperate desire of the many.