I started reading this story at a bookstore and couldn't put it down. Chiang's creativity makes the book feel more realistic as he introduces the concepts of digients or virtual "pets" who are ai through the eyes of an ex-zookeeper who joins a company that makes them. As we learn what digients are like from their care taker and trainer, we enter a fuzzy realm of when an ai based "pet" becomes authentic and real and at what point does this digital entity become mature enough to make its own decisions. Chiang's takes a lot of unexpected turns that creates a vibrant story with living human and digient characters.