Fictions already run counter to fact. Counterfactuals, in logic, philosophy, or history, imagine an alternative possible world, to test a theory, to prove an argument about contingency and necessity, or merely to explore the question, "What if?," like the Marvel comic book title.
The same approach can be taken to fiction, to imagine a book or a story where proper names still single out the same individuals but everything else is different. A book other than the book, a fictional fiction other than the fact of fiction. Fiction has its theories to be tested and other worlds to be explored.
So with counterfiction we ask "what if?" to our favorite stories, books, comics, and films, for fun and (non) profit. Some of our counterfictions we will write ourselves, and other entries will discuss counterfictions found in the wild. The point is to try to open up just a little more imaginative space in works of the imagination, and to make fiction live in fiction a little more brightly.