One of the recurring ideas in fan fiction is what is called “crossovers,” where you take characters, and sometimes aspects of, one author’s work (either a single work, or a series), and “cross” it with the base work for your fan fiction, that is embed the extra characters in the new universe to explore how the plot of one or both works would change.
The Addams family is interesting, because the original conception is from newspaper comic series that started in 1938, but most people remember them from either the 1960s television show, or one of the more recent movie reboots.1 If you use the 1991 movie as your starting point, Wednesday Addams is within a few years of [Harry]’s age, so it is a reasonable (that is, believable) use of artistic license to make her the same age. While any number of these works introduce disturbing gender-bending aspects that I would really rather have nothing to do with, some are very well done and quite amusing. They also bring into sharp focus the fact that Mrs. Rowling’s original work lacks any solidity to its moral framework.
[Harry]: </Harrypedia/people/Potter/Harry James/>/
Wikipedia has a synopsis of the various iterations of the family in the article “The Addams Family”.↩︎