The narrator can be described as darkly ironic, bitter, possibly paranoid, and perhaps slightly evil. The entire monologue is a discourse about his late wife who since her death has been reduced to nothing more than another one of his beautiful objects of art. He casually reveals to his visitor that he thought she could be swayed emotionally by minor things such as meaningless compliments or trivial pursuits.
He indicates that she had a wandering eye, and he implies that she was perhaps unfaithful to him. He does not seem to be bothered by her unfaithfulness to as much as he is bitter about the perceived disrespect her behavior cast upon the venerable name he conferred upon her with their marriage. There is evilness in the inference that he had this duchess killed when he states, "I gave commands;
Then all smiles stopped together. There she stands
As if alive," and there is even more to be concerned about when he immediately proceeds to talk about the young lady downstairs--possibly his next poor duchess.