Hamlet and Horatio bear a loyalty and filial love for each other exhibited by fulfillment of their respective roles as servant and master. Not having chosen these roles themselves, they fulfill them as a token of their good faith to each other through the convention of their times. It is Horatio who, knowing Hamlet's love for his father the departed king, first tells Hamlet of the appearance of his father's ghost beyond the platform. When they go together to behold the ghost, Horatio sees that Hamlet bears casual concern for his mortality -- "I do not set my life at a pin's fee...." To which, Horatio vociferously tries to persuade Hamlet not to go with the ghost; he even tries to physically restrain him with the help of Marcellus. Horatio appears to feel guilty and responsible for Hamlet should he come to harm. Especially if Hamlet was led to the ghost by Horatio's own honesty in reporting the news of his father's ghost. As a loyal...

Horatio's loyalty is again confirmed when he swears to keep Hamlet's confidence by any oath his master may require -- "Propose the oath, my lord."
Horatio's loyalty is reciprocated by Hamlet after taking the oath. Hamlet says, "With all my love I do command to meet you: and what so poor a man as Hamlet is may do, to express his love and friending to you, God willing, shall not lack. Let us go in together..."

It is not unreasonable to suppose that Horatio took great personal risk in his oath to Hamlet. Where Hamlet had rank and birthright to protect him from the new king, Horatio did not. By plotting with Hamlet to expose the king, Horatio may have been guilty of treason; and this after the king's disposition to murder was known to him. Horatio's sense of morality and loyalty to Hamlet bring him…