In a TED Talk, the Russian-born entrepreneur Eugenia Kuyda describes the sudden death of her best friend and housemate Roman, the “coolest person” she knew. Grieving and desperately lonely, she immersed herself in his old text messages. At the time, she was working in a conversational AI startup, and she experimented with training a new model using Roman’s text messages. Soon she was texting this model throughout the day, sharing jokes and observations. “It felt strange at times,” she concedes. “But it was also my healing.”