This is, essentially, how it happened with our cats. It's kind of a continuation of what happened with the pets my sister and I had growing up. We (as kids) made up stories, and our parents participated to some extent. We used to joke about making a book, "The Secret Life of Walter Kitty" (of course, someone else has done it, just checked). As adults, we just kind of continued it because, why not? It's entertaining and amusing just like any other story telling activity.