Ignatius Reilly is a slapstick hero. He conforms to all nine of the "Personality Traits of the Hero in a Physical Comedy" as detailed in the documentary "Laughing Matters" (see my blog entry from July of 2015). However, Ignatius is psychologically repressed. He defends his virginity. Despite being a physical comedian, he is learned, with intellectual pomposity.
Cosmo Kramer, a character on the 1990s sitcom "Seinfeld," is also a physical comedian. He falls, he crashes. He is an innocent fool who acts on his desires without worrying what others might think. He is not overly intellectual, and he is not pompous. On the show, many women are attracted to his honest expression of emotion (at least for brief relationships), much to the frustration of the other male characters. In season five, episode eleven, this sexual charisma is called "the kavorka."
Ignatius and Kramer can function in similar ways in a farcical plot. Both of them generate chaos in the social group which can reorder relationships. As I have stated in detail before, comedies often feature a small group where some members are lower in the status hierarchy than they should be, held down by a blocking character. The comic chaos reorders the relationships with the blocking character losing status and the deserving oppressed rising in status.
To give an example from Seinfeld, in season three, episode seven, called "The Cafe," George is trying to impress the woman he is dating, who is an educational psychologist, even though he does badly on intelligence tests. He agrees to take an IQ test, but then he passes the test out the window to Elaine, who is good at taking such tests. Elaine goes to the cafe to take the test. Kramer comes into the cafe, interacts with Elaine, and spills food on the test. George cannot pretend that he took the test. His false presentation as a smart person is undone by the chaos generated by the slapstick hero. His status is comically lowered in the estimation of a potential mate, thanks to the slapstick hero.
Thesis: Compare Ignatius Reilly to Cosmo Kramer. They are very different but can function in similar ways within the plot of a comic narrative.