In "Grande Size Me", Duff is among the villains who appear at the HenchCo auction, and express actual concern for Ron upon noticing the sidekick's dramatic weight gain. Later, in "Graduation," Duff is initially suspected of vandalizing various country clubs and golf courses around the world. However, Kim and Ron discover that Duff's island has likewise been marred by a large symbol, which is later revealed to be a Lorwardian emblem foreshadowing their invasion. While Kim investigates, Duff questions Ron about their relationship, exacerbating Ron's growing insecurity over his imminent graduation from high school.