The lunar rovers she built as a student at Carnegie Mellon, and the software she developed as an engineer for Google—that stuff was just practice. The things Yun really wanted to make were friends.

Yun had hungered for companionship since she was a little girl in China. She'd begged her parents for a pet, but no dice. These were the days of China's one-child policy, so no sibling either. Instead, Yun's parents filled her room with a menagerie of stuffed animals, which she liked to imagine springing to life, their little paws dancing on her bedspread, their little bodies stuffed with possibilities.

In 2017, Yun quit her job at Google to start building the friend she'd always wanted. She started a company, called Zoetic, and recruited a few other roboticists to take her imaginary sidekick and turn it into a commercial product.