Horatio, despite considerable stage time in Hamlet, is a rather unappealing role for actors. The reason is that nothing happens to him, plotwise, in the play—he has no dramatic arc, as actors call it, no change of situation, no growth or development as a character. The reason is that he is a dramatic “device,” a sounding board for Hamlet’s outer reactions, a recipient of Hamlet’s utterances. In a play replete with inner monologues, there must be some speech-acts for Hamlet to utter, and since the play is filled with duplicitous, untrustworthy characters (Polonius, Rosenkrantz and Guildenstern, etc.), there has to be one character to whom Hamlet can utter the non-ironic truth, a loyal peer who will listen without an agenda (and with whom the audience can identify.) If you look at his actions in the play, you will see how passive and receptive and nonjudgmental he is. For example, “Alas, poor Yorick/ I knew him, Horatio…” elicits no reaction, despite the dramatic strength of the scene itself. Scholars have invented the term “Horatio character” to discuss this device in other pieces, meaning a character whose function is to allow another to utter speech-acts–accusations, questions, promises, doubts, etc., etc. Many times the “Horatio character” is a court fool, a best friend, or a wise older person (Juliet's nurse, for example). Because, by definition, drama is without narrator, the "Horatio character" lets certain information be uttered for the audience to hear. One major function of Horatio in Hamlet is to show that Hamlet is not really mad, but is sometimes feigning madness.