Mutation

In "Mutation" by K.A. Applegate, the main characters Jobs, Mo'Steel, Billy Weir, and other Remnants continue to struggle for survival within the imaginary worlds created by Mother, the sentient computer that controls their reality. While exploring, they encounter new Remnants including Kubric DiSalvo, whose skin has been replaced with a transparent plastic covering. The group also discovers one of the new Remnants has undergone a strange mutation that has transformed him into a dangerous monster, adding a new threat to their already perilous existence.