Mr. Marvel, a character initially described as something of a loner who is mentally slow and impoverished, becomes admired, wise, and so rich that he is described as a “treasure trove” at the end of the novel. This, in turn, functions as situational irony in the novel.
Griffin initially approaches Mr. Marvel because he is an outcast. He appears on a completely empty road. He has no companions, job, nor prospects. However, because something terrible happens to him (that is, the Invisible Man forces him to be his accomplice), he ultimately becomes rich. Marvel reverses his own fortune by stealing money and the notebooks from Griffin, despite the knowledge that it will get him killed.
By becoming known as wise, one of the core aspects of his character is reversed. Mr. Marvel struggles to recall the Latin phrase “vox et praeterea nihil,” meaning "a voice and nothing else," but he stops at "et" before exclaiming "jabber," denoting that he is an individual who tries to be intellectual but, due to a lack of education, falls just short of the mark.
Marvel is slow to believe in the Invisible Man, not because of well-considered skepticism like the type of disbelief Doctor Kemp shows, but because of confusion. Marvel seems to be motivated by pain and fear rather than impartial considerations of scientific evidence. By the end of the novel, however, he gains an intellectualism in the eyes of others. Mr. Marvel’s evolution into someone known for his wisdom is a reversal of readers' expectations and, in this way, is ironic.
