In his Symposium, Plato, writing in the character of the madman/friend of Socrates, Apollodorus, is asked by an unknown companion to tell what he knows about a feast during which Socrates and others delivered speeches in praise of love. Apollodorus, the events fresh in his memory from having recently recounted them to Glaucon, agrees and proceeds to tell his traveling companion of the seven speeches.
I believe it is clear that Socrates is indeed the main character of the work. Plato, in choosing Apollodorus as his mouthpiece in Symposium, sets the tone for the piece to revolve around Socrates. Apollodorus is described by the companion as having a reputation for, "always speaking evil of yourself, and of others; and I do believe that you pity all mankind, with the exception of Socrates...for you are always raging against yourself and everybody but Socrates". This establishes Apollodorus as having a bias toward Socrates, a bias that remains consistent throughout the piece. Through Apollodorus, Plato tells the story in the second generation. That is, Apollodorus tells the unknown companion what he was told by Aristodemus, who himself accompanied Socrates to Agathon_s banquet where the discussion occurred. Aristodemus too, was an admirer of Socrates which only goes to deepen the bias.
Aristodemus tells Apollodorus in Symposium that he met Socrates on the road, "fresh from the bath and sandalled", the first physical description of Socrates in the piece. When asked where he is going dressed so well, Socrates replies, "To a banquet at Agathon_s, whose invitation to his sacrifice of victory I refused yesterday, fearing a crowd, but promising that I would come today instead; and so I have put on my finery, because he is such a fine man". In this brief description, Plato succeeds in setting the tone of the banquet itself as one during which Socrates is a much desired guest.