George Michael matured in public, from cocky rapper to gleeful soul singer to thoughtful crooner. He continued to take on new musical ideas—such as his mash-up cover “Killer / Papa Was a Rollin' Stone”—with a voraciousness similar to that of his beloved Stevie Wonder, and as his voice blossomed, he never lost his social conscience or his capacity for sexually charged pop, as in “Freeek! ‘04.”