In the world of Apocalyptus, everyone is a mutant. There are good mutants and there are bad mutants, and most of the time the distinction is pretty obvious due to the bad mutants usually being deformed, and the good mutants usually being clean and attractive.
The evil mutants are called The Affected, and they live almost exclusively on the surface. They have mutated into a lot of distinct groups with vastly different behavioral patterns. Here we see Affected Misers, who are consumed by unnatural greed and unnatural stinginess. Many other types of Affected exist, including Affected Beggars, Affected Constables, Affected Convicts, Affected Whalers and so on. Every group has its own unique psychology, and its own unique form of community.
Some of the more powerful Affected are more distinctively individual, and most of them happen to be well-known historical and literary figures. For instance, Affected Captain Ahab, who drives his crew to hunt the Affected White Whale on land and sea, and Affected Geppetto, who has the power to animate any wooden object he pleases. Some of the major Affected are original creations, such as an Affected crime lord who calls himself The Nucracker, due to the severe deformities to his face that cause him to resemble the popular wooden toy.
The good mutants call themselves The Trueborn (Or "Breathers" as a pejorative nickname by The Affected). They are filled with radioactive power, and are able to perform fantastic feats. Some of them have physical strength, others have crazy powers, and some are even psychic. They break up pretty cleanly into a number of character classes that we've set up. The Trueborn live in a number of safe places, most in the air, some underground, and some at sea.
Moral lines between the two sides are blurry at times. Affected Sherlock Holmes, for instance, is an upstanding, but reclusive character who keeps his mind from deteriorating into corruption using cocaine. Deathrantula, on the other hand, is a Trueborn steam mage, and a highly educated one, who turned his back on the Trueborn for reasons unknown. The Nukeromancers are an entire character class who dabbles in the dark side of radiation for incredible power. Over time they gain deformities and become themselves affected.