Counterfactuals and Truth in Fiction

David Lewis thinks that what's true in the fiction is what's true in the nearest possible worlds in which the story is told as known fact, instead of as fiction. So, here's a fictional text:

Once upon a time, there was a guy named Andy who liked to eat candy. His best friend was Sandy. And he and Sandy found it handy to steal candy from Walmart. The end.

That was a fiction, so I was doing something different from telling you something I know; you misunderstand me if you treat my story as testimony and form all these beliefs about Andy and Sandy. But you can understand what it would be like if I were really making assertions about what I know about; you can make judgments about what would be true if (what is true in the nearest possible worlds in which) my story were a piece of true non-fiction, instead of a fiction. On Lewis's view, that's what's true in the fiction. There have been lots of good criticisms of this view -- I think this may be a new one. Suppose that in fact, just by coincidence, all the sentences that make up my story happen to be true. There really is some guy, maybe in South Dakota, whose name is Andy, etc. His mother works as a substitute teacher. I, the story-teller, have never even heard of this guy; I'm just making up a fiction. Now, what is the implication of Lewis's view? Consider the nearest worlds in which I'm telling the story as known fact. Well, there are two candidate classes of worlds -- worlds in which I know about the guy in South Dakota and am talking about him, and worlds in which I know about some additional person who meets the description. It seems very plausible that the former worlds are the closer ones; in the latter worlds, we need an additional person named Andy who likes Candy and steals from Walmart with Sandy. So in the closest worlds in which I know the story, I'm talking about this guy in South Dakota. So, it's true in the fiction that Andy lives in South Dakota, that his mother is a substitute teacher, etc. This is intuitively wrong; whether there's some guy satisfying my story who is nevertheless causally isolated from me has no bearing on what is true in my fiction; to learn what is true in the fiction, we need not investigate whether anyone satisfies it in the actual world.