The Invisible Man
Marvel makes a pretty lousy companion for the Invisible Man. How lousy? Well, he runs away right when the IM needs him the most. In fact, although he helps the Invisible Man with some of his schemes, Marvel ultimately betrays the guy. Goes to show you: the Invisible Man isn't good at making friends, even with a homeless dude who doesn't have anything else in the world. So, Marvel is a companion for a few chapters, but what's more important is that he stops being a companion. That really tells us a lot about the Invisible Man, who isn't able to keep any friends (throwing stones doesn't help).