You don't learn a whole lot about Babo directly. Through most of the novella, you see him supporting Don Benito, apparently servile and helpful. And then, all of a sudden, at the end, you learn that he's a desperate, brilliant strategist, who managed to fool Delano for the entire novella, and almost captured a second ship and saved his people.
When you go back through, you see some evidence that his head is the "hive of subtlety" (3.433). In particular, that moment when Babo cuts Benito shaving, and declares "See, master—you shook so—here's Babo's first blood." (3.266) No wonder Don Benito goes pale; given the situation, that is an awfully, impressively cool, subtle, and brutal threat.
But while you can see Babo's intelligence and ruthlessness, the novella doesn't show you his other qualities. You have to interpolate them. How courageous, quick-witted, and desperate must he have been to have plotted the takeover? How must he have hoped after the overthrow that the ship could take them home? What despair must he have felt as the days slipped by, and how he must have finally hoped, desperately, at last, that they could outfox this new Captain Delano, kill the evil white men who threatened them, and finally achieve freedom for his people. We get to see Babo as a genius you see; yet we can only imagine Babo as a freedom fighter—not to mention as a tragic hero and martyr.