The Devil's Alphabet

From Daryl Gregory, whose Pandemonium was one of the most exciting debut novels in memory, comes an astonishing work of soaring imaginative power that breaks new ground in contemporary fantasy.Switchcreek was a normal town in eastern Tennessee until a mysterious disease killed a third of its residents and mutated most of the rest into monstrous oddities. Then, as quickly and inexplicably as it had struck, the disease--dubbed Transcription Divergence Syndrome (TDS)--vanished, leaving behind a population divided into three new branches of humanity: giant gray-skinned argos, hairless seal-like betas, and grotesquely obese charlies.Paxton Abel Martin was fourteen when TDS struck, killing his mother, transforming his preacher father into a charlie, and changing one of his best friends, Jo Lynn, into a beta. But Pax was one of the few who didn't change. He remained as normal as ever. At least on the outside.Having fled shortly after the pandemic, Pax now returns to Switchcreek fifteen years later, following the suicide of Jo Lynn. What he finds is a town seething with secrets, among which murder may well be numbered.

Synopsis from Open Library.