Adan's discovery

We just received our pile of books that we order each month from scholastic. We typically read all the books we've purchased for the month all at once. We traditionally have some character books (Diego, Scooby etc) in the batch. I of course have to add books that have a little more substance to the collection. Hence the reason we have a stack of books each month. Mateo typically orders a Scooby pack each month. So we sat down to read the three Scooby books in the pack. After two of the Scooby books had been read, Adan looks at me and says, " that is fake." I reply by saying, "what is fake?" "The Scooby books are all fake. Mom, why are the Scooby books fake?" What am I suppose to say to my five year old who has been obsessed with Scooby for a year now? We own several seasons of the cartoons, and at least 20+ books. So my response to it is, "Scooby and Shaggy have good imaginations. His response. Why is Scooby fake? Now he is just disappointed to have had this discovery. Who knows if he will be as obsessed with it. Mateo's response to this all. Scooby is fake! I am surprised Mateo stated the facts and didn't ask questions.