For most of the movie, he is referred to as The Doctor, a scientist working with James McCullen concerning his research on nanomites. It is revealed that he was Rexford G. "Rex" Lewis, the younger brother of Ana Lewis, and once a soldier alongside Duke. Rex was presumed dead, after a building Duke sent him into was hit with a premature air strike called in by Duke. But prior to the explosion, Rex saw McCullen's early experimental research on nanomites conducted by Doctor Mindbender, and was in awe of the sight. Surviving the incident, yet scarred both physically and mentally; requiring a special mask to breathe, Rex learns from Mindbender and perfects the nanomites. He uses his own sister as a test subject in creating the Neo-Vipers, making her an agent known as the Baroness. He carries a deep grudge against Duke for leaving him to die. When Duke is captured, Rex reveals himself, as he attempts to subject Duke to the nanomites and make him one of his Neo-Viper soldiers. But the Baroness overcomes her programming and saves Duke, while Rex escapes with a badly burned McCullen. Rex uses specially made nanomites to heal McCullen's face, which also encases it in a living, silver-like metal. Dubbing him "Destro", Rex puts on a new breathing mask and tells McCullen to call him Commander. Although he is arrested and placed in a high security prison aboard the USS Flagg, Cobra Commander's master plan had only begun, with Zartan disguised as the President of the United States.