Answer:
Carter Druse - The story's protagonist, he is the only child of wealthy Virginia parents who decides to join the Union regiment that arrived in Grafton, Virginia, a few miles from their home. His action makes him a traitor to Virginia (according to his father) and breaks his heart. The Union officers assign Carter to a remote outpost as sentinel since he knows the terrain and they are impressed by his "deeds of devotion and daring." He betrays them by falling asleep on duty.
Carter's Father - A wealthy landowner in Western Virginia whose only son announced he is joining the Union, to which he replied, "Well, go, sir, and whatever may occur do what you conceive to be your duty." His father promises they will speak more of the matter should they both live to the end of the war (that was prescient). The father is both staunchly reserved (does not show emotion), and reveres duty and family.
Explanation:
The Horseman - The identity of the rider is not revealed until the end of the story, when we learn it's Druse's father, a Confederate spy. Likened to a god, collosal in magnitude and seemingly having spiritual powers, Carter shoots him to avoid allowing him to reveal the Union regiment's position he's guarding in the valley below.
Carter's Mother - Though she never appears in the story, Carter's father reminds him that she is critically ill and will die in a few weeks. The young Druse does not announce his decision or say goodbye to her, at his father's insistence, due to her fragile condition.
The Officer - The only witness to the death of Druse's father, whom he sees falling over a thousand foot vertical cliff, appearing to fly as an apparition. He gave up searching for the body and horse and failed to report it.
Sargeant - The officer who hears the shot and interviews Druse, who confesses that the man he shot was his father, horrifying the sargeant.
The Angel - The unseen force that wakens Druse from his sentry slumber, just in time to spy the Confederate spy undetected
