In The Simpsons / Futurama Crossover Crisis II, #2 (2005), a vortex brings the characters in the New York Public Library's fiction section-- and the Simpsons-- into the world of Futurama. Since they aren't "real" people, the fictional characters are enslaved, and they quickly rebel. Here, Fry and Bart dodge some angry-- and familiar-- superheroes. The story acknowledges that this isn't a licensed crossover, but the writer clearly understands the conventions of superhero crossovers, as the two groups fight each other, literally at the drop of a hat.