We’re now more than halfway through Barbara Kingsolver’s “Demon Copperhead,” and we’ve watched our narrator Demon go from a childhood of abuse and neglect to high school football stardom. He is worshipped by all of Lee County, Virginia — and even falls in love for the first time — and then a serious knee injury during a game alters the course of his life. He’s given prescription painkillers by his team doctor, becomes addicted, drops out of school, and begins selling drugs to survive. Demon’s fa