Character Analysis
Captain Nicholl and President Barbicane's rivalry is about as fierce as they come. Their relationship is simple—"when Barbicane invented a new shot, Nicholl invented a new armour-plate" (10.9). It's tit for tat with these two, since each man thinks the other is his mortal enemy, working harder and harder just to spite him. But the reality is a little more complicated.
Would either man have reached his full potential without the other spurring him on? Would Barbicane have invented such amazing cannons if Nicholl's innovation hadn't forced him to? Although each sees the other as the embodiment of evil, the truth is that each man is at least partially responsible for the other's success. Out of a refusal to be bested by the other, each man pushes himself to new heights.
Ardan can see this, even if Nicholl and Barbicane can't. See, Ardan knows that Nicholl is a good dude after witnessing him save a bird "caught in the web of the monstrous spider" (21.43). This fits in perfectly with his personality—while Barbicane is driven by a need to destroy, Nicholl is driven by a need to protect (hence all that armor making). It's then that Ardan realizes the incredible potential of these two foes coming together.
Ultimately, with the help of Ardan, Nicholl and Barbicane join forces to create a dream team of scientific explorers. Now these two men who tried to kill each other just days ago, are planning on launching into space together. It's kind of nuts, right? But it's just a reminder that sometimes the people we hate the most are the people who are most similar to us. Still, we're thinking it's good Ardan's stuck circling the moon with these two—who knows what would happen otherwise.