As with Superman: Red Son, Millar claims that the concept for the series occurred to him when he was a child. In this case, it came to him after his brother told him that there were no superheroes any more because they had all disappeared after a great war with their respective supervillains. It was modified from a pitch by Millar for a Secret Society of Super-Villains series.
1986, the year of the aforementioned war in which the supervillains took over and made their world “darker and grittier”, has real world significance to the world of comic books. It marks the publication of Batman: The Dark Knight Returns, Watchmen, and the completion of the 1985-86 Crisis on Infinite Earths series.