He has stated that Optimus is his favorite voice role, and that he based the voice of the Autobot leader on his older brother Larry, who served in Vietnam. "When he came home, I could see a change. He was quieter and he was a man and a superhero to me," says the actor. "I watched him and listened to him. I'd never had an opportunity to do a superhero, and when that came, voice just came right out of me and I sounded like Optimus."