"A," or Johannes Climacus
This fictional author is the pseudonym for the first part of Either/Or. We don't learn his name until we read a sample of his writing and then, later, we learn from The Judge that "A" is in fact Johannes Climacus. Climacus is a serial monogamist who enjoys luring girls into his life, but then once he wins their hearts, he gets bored and breaks up with them. His life is shaped by Aestheticism, or the attempt to gain pleasure from experience.
"B," or The Judge
The name "The Judge" is a not-so-subtle reference to divine judgment or wrath, especially since it's written by Søren Kierkegaard. This hypothetical character is a voice of reason, speaking to Johannes as a bachelor, encouraging him to find the wisdom to switch from being entertained by life (Aestheticism) to fulfilling the intentions of a human life (Ethics). The switch toward Ethics involves the story of Johannes becoming married.
Cordelia
This fictional character represents a real person, perhaps even Kierkegaard's ex-fiancee. Cordelia is incredibly beautiful, and Johannes finds deep meaning in his attraction toward her, but he realizes that the most fun part is the chase, so Cordelia is completely blindsided when Johannes dumps her for boring him.
