Isaac

Isaac McDougal is a former State Alchemist, stripped of his title and standing, who has spent years nursing a grudge against the military that discarded him. Calling himself the Freezing Alchemist, he confronts Edward and Alphonse in the snowbound north, determined to prove that his ice-based alchemy — and his resentment — are far from finished.

He's only a brief obstacle, but the writing uses him efficiently: a man chewed up by the same State Alchemist system Edward serves, bitter proof that the military's use of alchemists has victims beyond the obvious ones. Yamadera gives him a hoarse, wounded fury that makes his single arc land harder than his screen time suggests.