Both Ignatius Reilly of Confederacy of Dunces and Buddy from Elf are immature, slapstick heroes whose disruptive behavior upsets a dysfunctional social order, allowing a comic happy ending.
Thesis: Compare Ignatius from Confederacy of Dunces to Buddy in the movie Elf.
My Initial Thoughts:
There is a huge difference between both those two characters and their narratives. Buddy is a more sympathetic man who is honest in his attraction to women and who, in the end, inspires faith in others and gets the girl. His actions help get his father to decide to quit his high-paid job where he was dishonest, start his own company, and spend more time caring for his family.
Ignatius, by contrast, is more of a pompous rogue and a trickster. He is childish, rather than child-like. Even at the end of the book, he thinks he is using Myrna as a vehicle for escape rather than genuinely forming a new relationship. Confederacy also has a more sustained and sharp criticism of modern consumer culture. Some of Ignatius's observations about the society around him hit the mark, while Elf promotes consumerism. But Ignatius's own position is ludicrous, thereby allowing a critique of Renaissance humanistic ideas as well.
Bottom line: The plots have some comic similarities, but Confederacy is more complex both in its ideas and in its ending.
Google Scholar still has not added the Research Gate link to this paper: Evidence of influences on John Kennedy Toole's "A Confederacy of Dunces," including Geoffrey Chaucer. Get to it, people.