Stannis is barely reacting to his presence, and boy, doesn't that feel familiar? He remembers much the same from his early childhood, constantly being underfoot looking for attention and his brother refusing to provide. That was, of course, before he just up and left.

"Spirit?" He sounds indignant, because of course he does. "I am no spirit, no matter how you would like to ignore my existence! Do not insult me so."

And then to further prove that he is not a ghost, he takes the chair leg and he strikes out at Stannis with it, a pretty clumsy swipe that's more to get his attention than do any real damage. "You have many things to apologize for, but I have long given up on expecting one, brother."