George is not the brightest kid out there. Unlike Horace, though, he at least makes an effort to blend in, like by "wearing the kind of baggy, oversized, swamp-colored clothes that you see on most sixteen-year-olds these days" (2.22). While he's bright enough to figure out how to pass unnoticed in society, though, he's not too smart. As Nina observes: "One look at his gormless, waxy, nondescript face is enough to tell you that he's not exactly the sharpest tool in the box" (2.35). But he's a vamp, so he's part of their group—they really have to stick together to survive.
George was a "teenage boilermaker's apprentice" (3.9) when he got bit, and since then, he's become the group's guinea pig breeder, so he pulls his weight. When Horace is confined as punishment, though, it leaves George a little lonely because they'd been roomies. Poor guy.