Nero is Saba's pet crow. That wouldn't be anything to write home about, maybe, but Nero also happens to be pretty exceptional—"more like a person than a bird," according to Saba (6.755-756). He can communicate, pass messages across vast distances, and even play dice. It's impressive stuff. As you can imagine, Nero's abilities come in quite handy over the course of the novel, but hey, most importantly, he really gives Saba some cool "post-apocalyptic chic" mystique.