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Character Role Analysis
Cypher and Trinity
Cypher and Trinity are probably more alike than you realize. They are both redpills, after all. They both were somehow discontent with the Matrix; they had an inkling of something more and were tracked down and rescued by Morpheus. They're also both working on the Nebuchadnezzar and, given that Cypher's been in the real world for nine years, we assume that he's only there by choice (or lack of a better one).
Of course, the differences are the important part. Trinity is loyal to Morpheus and trusts his belief. Notice that not until Trinity falls in love with Neo does she confirm her own belief in the prophecy, but she cites Morpheus' belief as reason enough for her.
Cypher, on the other hand, hates Morpheus. More than anything, the reason he wants back into the Matrix is to escape the man who set him "free." Cypher is tired of fighting, tired of being on the ship, tired of the cold, and tired of eating the same food every day, but more than all of that combined, he's tired of listening to Morpheus. His betrayal is self-serving, but it's also an act of revenge.