Horatio a figment of imagination?

Horatio spends most of the play talking to Hamlet, and he seems to be the only one privy to all of Hamlet's actions of revenge. Horatio is of course, a real character, as he has minor and unimportant lines addressed to the Queen, Osric, and Fortinbras. But a large part of his character serves only to provide the couch on which Hamlet lays as he confesses all his thoughts to his psychiatrist. He never gives very definitive opinions, and sometimes only addresses Hamlet, though other characters are in the scene at the same time. Just before the play, Hamlet speaks to Horatio saying, "There is a play tonight before the king. One scene of it comes near the circumstance which I have told thee of my father's death." But I looked back, and Hamlet has no interaction with Horatio between this moment, and when he asks him to swear never to tell about seeing the ghost. Hamlet never explicitly told Horatio about the ghost's plan for revenge. Unless, of course, this conversation with Horatio is supposed to refer to a conversation that really did happen, but was never shown? Horatio happens to also be the only person to whom Hamlet shows any affection. I wonder if maybe Horatio could be partially imagined, at least the Horatio that helps Hamlet more clearly form his ideas and implores him to be cautious at times. What do you think? Could Jimminy-Cricket-Horatio really be a projection of Hamlet's revenge, or maybe his actual conscience?