Overview
Although Haruhi Suzumiya is the title character of the series, the main protagonist of the story is Kyon, and it's told from his point of view. He narrates with sarcastic commentary on the various absurdities that arise around Haruhi and the SOS Brigade's activities. Kyon's narration follows the format of a Greek Chorus, speaking directly to the audience through internal dialogue. Kyon may also direct his thoughts at Haruhi, to which she occasionally responds to, making it unclear whether he is speaking aloud or merely thinking to himself. This could also be interpreted as Haruhi having a nearly telepathic empathy with Kyon. Though a self-described barely-above-average student, Kyon; particularly in the light novels, very often peppers his narration and dialogue with references to ancient mythology, advanced scientific concepts (such as the laws of thermodynamics, the theory of relativity, etc.), both well-known and obscure pop culture (he identifies a Marilyn Manson song Haruhi hums in the second light novel), and various esoteric subjects, often comparing the Brigade's situation to a typical role playing game.
He is also the only "normal" human in a club otherwise assembled to include membership from an alien, esper, and a time traveler. This is a cause of curiosity and concern amongst several third parties, since Haruhi is "not interested in ordinary humans". Yuki Nagato refers to Kyon as an "irregular factor near Haruhi", responsible for an abrupt change in the data around her. Itsuki Koizumi goes so far as to investigate Kyon's identity, only to affirm that Kyon is indeed an ordinary human. Ryoko Asakura herself is quite puzzled by Haruhi's interest in Kyon and asks how it was that he has gotten Haruhi to open up.
He is quite intelligent and can be very observant, despite his average grades. It is Kyon who solves the murder mystery during the events of the Lonely Island in the light novel, not Haruhi (even though, characteristically enough, she takes the credit for it). He says that he had known (though implying that this was only about someone not dying) the truth since the beginning; as he does not believe that Haruhi would wish for someone to die, and comes to the truth after he notices several falsities.
In an interview with Nagaru Tanigawa, the author admitted that Kyon was supposed to be portrayed as an esper in his original conception, but while writing The Melancholy of Haruhi Suzumiya, Kyon was instead changed into an ordinary student.
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