Gus is the antagonist in the story, set to kill the main character or else the little girl he babysits dies, maybe this time, he make himself a true hero.
Fauns were used in the war as kamikaze, catapult ammo, they were thrown into the battle heads first, causing massive damage with their rock solid heads, dead or alive, they were consider heroes, not Gus. The fear of dying led him to desert the war, and this world doesn't take kinldy to cowards, knowing that, and afraid of judgment, he fled his hometown, and found sympathy on a mother who knew well enough, what happens when you deny control to the high classes, and that's how he bacame a babysitter.