The character of Axel is not that of the ordinary hoodlum. Grat has created an extraordinary thug; one who means to rule the world. It's no accident that this character mirrors Hitler's intentions. Axel becomes a Hitler-type character, but on a level that's closer to home. Annie makes the discovery of Axel's intentions while in captivity.
Nick figures to take care of Axel once and for all, in the hero-type way which Gray admired.