Just like our boy Aronnax, Nemo's name packs a literary punch. It alerts us readers to the fact that Nemo is larger than (fictionalized) life; he's not just a character, he's a symbol (see our "Symbols, Imagery, Allegory" section for more information). What's he a symbol of, you ask?
Well, Nemo means "no one" in Latin. So his middle name might as well be mystery. Clearly, Verne wants us to be curious about Nemo's past. We empathize deeply with Aronnax's incessant questions about Nemo's true identity, because the dude's utter out-there-ness has kept us up at night, too.
At the end of the novel, when all is usually revealed, we are left only with Aronnax's remaining questions about his Captain:
Is Captain Nemo still alive? [...] Will the waves one day wash up the manuscript containing the entire story of his life? Will I finally discover his name? Will the nationality of the vessel sunk tell us Captain Nemo's own nationality? (2.23.5)
So we guess we'll have to wait 'till Nemo's tell-all comes out before we can get some darn answers around here, huh? Nah, don't give up on Verne (or us) too soon, dear Shmoopers. Maybe the important thing about Nemo is his enigmatic nature.
Allow us to prove it to you. First, he's a private person. He built his own special submarine just so he could be alone, away from society. He famously says:
I am not what you call a civilized being! I have broken with society for reasons which I alone have the right to appreciate. So I do not obey its rules, and I ask you never to invoke them in my presence again! (1.10.20)
Nemo won't even surface to bury his dead crewmen. He puts them to rest in a massive undersea cemetery. Aronnax seems to think that Nemo buries the bodies under the sand so that they will be "out of the reach of sharks." But Captain Nemo wryly points out that it isn't just the sharks he's worried about; in this cemetery, his dead men will be safe from both "sharks and men!" (1.24.76-7).
We never do learn where that warship at the end of the novel was from. Or if Nemo was actually an American Civil War veteran. The fact is, no man (or woman)—us readers included—can get the truth out of him. And this mystery is precisely what allows Nemo to become more than a man in 20,000 Leagues.
After Nemo destroys the mystery battleship near the end of the novel, Aronnax notes:
His character was accentuated and took on a superhuman dimension. He was no longer a fellow human, but a marine being, a spirit of the seas. (22.37)
Aronnax doesn't mean Nemo's a superhero. Although, he would become one in The League of Extraordinary Gentlemen. Come to think of it, he also shares some similarities with Aquaman, who, depending on whom you ask, may or may not be the son of Nemo.
Anyway, Aronnax is really pointing out that Nemo's more myth—more story, more gossip—than man. And this larger-than-life image of Mr. Nemo wouldn't hold water (hilarious, we know) if we knew some more real facts about Nemo's life.
Like, if we were to learn that Nemo was actually from Cleveland, Ohio, where he's got a wife and two kids waiting for him to come home, he wouldn't seem so special after all. In order to be No One, Nemo has to be a kind of an everyman.
Considering his position outside—and maybe even "above"—mankind, it's not so surprising that Nemo makes proclamations like "I am the law, I am the justice!" (21.59). In the end, he's a man who's lost his country, his family, and his old identity.
There's no use digging into Nemo's past because by the time we meet him, his past has become sort of irrelevant. Now, he's simply Nemo, No One, a maritime ball o' questionably-motivated violence—and nothing more.Captain Nemo's Timeline