In “Marionettes, Inc.” Braling Two serves as a foil to his creator, Braling. The man built to imitate Braling ends up being more emotionally expressive and affectionate than Braling himself, which ultimately highlights Braling's negative traits.
Braling is emotionally closed off. He sees marriage as a burden, saying that his wife has “been nervous ever since we were married.” He wants space so badly that he is willing to secretly replace himself with a robot to avoid her. Braling Two, however, surprises his creator by forming his own attachments. When Braling asks him to take care of his wife, Braling Two replies:
"I'm afraid you don't understand. I think—I'm in love with her."
This reversal, where the robot is more human than the man, puts Braling’s emotional detachment in the spotlight. The foil highlights how disconnected Braling has become from basic feelings like love and desire. Braling intended Braling Two to be a perfect imitation of himself, yet the marionette transcends his creator's limitations.
Bradbury also uses the foil to heighten the story’s uncanny atmosphere. The robot isn’t just acting; he feels. This blurs the line between that which is artificial and that which is real, suggesting that traits like longing and attachment might not be exclusive to humans after all.