Multiple Narrators: Conflict of Interest
Cloud Atlas transitions between six different narrators, each from different time period, and none of them are reliable. Robert Frobisher doubts the veracity of Adam Ewing's journal. Luisa Rey's third-person story might be fictional (and what do we know about Hilary V. Hush, the pseudonymous author of this spy novel?). If it is, does that mean Frobisher is fictional too? Timothy Cavendish is about as trustworthy as we can throw him (not far) and Sonmi has calculated her entire interview to be persuasive toward her cause. Finally, Zachry is a gifted storyteller, and no good story is without a few embellishments.
So what's the point of having all these liars tell us their stories? Well, we're being harsh when we say liar. In all honesty (see what we did there?) how many people do you know who are 100% honest? If anything, the ambiguous motives of our narrators makes them more real.
Also, we see an interesting progression as we switch narrators. Each narrator seems to be a little less internally conflicted than the last. Poor Adam Ewing is such a mess of white guilt he doesn't even realize it. Robert Frobisher, too, is conflicted between art, money, and love. Luisa Rey is pretty single-minded (maybe due to her being fictional) in her pursuit of the truth. Cavendish is awfully sure of himself, despite being kind of a despicable old bat. And Sonmi-451 knows exactly what she wants, at least in this point in time.
Then we get to Zachry, who might be the most conflicted of them all. Perhaps that's because he's not one of the comet-birthmark-bearing narrators who may or may not be reincarnated souls, or maybe it's because history is cyclical and starting to repeat itself. Or maybe it's because he's just more interesting that way. Conflict also makes a good story. We like conflict.