is a sadistic psychopath.  Theatmosphere covers the jealousy, murder, manipulation, and insanity of the Duke.  He conveys his innermost thoughts about his disdain for his last wife.

Paraphrase

The Duke shows the painting, painted on a wall of his last wife to the servant of a Count. He keeps the picture covered by with a curtain that only he draws. The Duke is negotiating a marriage between himself and a count   The picture, painted by a famous painter Fra Pandolf, had many people who asked why she had the look on her face and is so life-like that it looks as though she is alive.  .

Strangers like you that pictured countenance,

The depth and passion of its earnest glance,

But to me they turned (since none puts by

The curtain I have drawn for you, but I),  

Strangers that look at the picture as if to ask why does she have the deep, passionate expression on her face. 

How did such a countenance occur? It was not just her husband that caused the happy blush that came on her face. The artist said that it might have happened because of a cape that covered her wrist.  No painter could ever reproduce that flushed look around her neck. She was courteous and that called up the blush. 

She had too much heart and was too easily impressed.  Whatever she looked at she liked. The Duke looking at her breast, the sunset, the cherry limb that some idiot broke in the orchard for her, a white mule that she rode—all were given a positive acknowledgement or her spot of joy. 

Often, she thanked men but no one knows how. The gift that the Duke gave her which was an ancestral 900 years old aristocratic name which she was treated the same as anyone else’s gift. Who would stoop to discuss this with her?

If a man had speech skills which the Duke says that he does not, he would tell that her behavior is disgusting and teach her how to act.  She needs to be taught to use her wits. There would be some kneeling down, but the Duke does not stoop for anyone.

Every time that the Duke saw her, she smiled at him; however, other men passed her and she smiled at them as well. This smiling at others continued and grew.  The Duke gave an ultimatum for her to stop smiling and then everything stopped. In the picture, there she stands as though she were alive.

The Duke asks the man to stand and return to the company that was down stairs. The Count’s generosity is absolute so that the Duke knows that he will get a fair dowry.   

It is not the dowry in which the Duke is interested, but rather the Count’s beautiful daughter. 

Now the Duke and the servant will go down together. As they leave, the Duke tells the man to take note of a statue of 1Neptune, the Roman god of the seas, who is riding and taming a seahorse. Another artist cast the statue in bronze and it is rare.

It is hard to say that the Duchess was flirtatious.  Perhaps she was only friendly and in love with life.  Either way, the Duke wanted her to only show affection to HIM.  Take a look at the lines below and make your own judgment:

She had a heart--how shall I say?--too soon made glad, too easily impressed; she liked whate'er she looked on, and her lookes went everywhere.  Sir, 'twas all one! My favor at her breast, the dropping of the daylight in the West, the bough of cherries some officious fool broke in the orchard for her, the white mule she rode with round the terrace--all and each would draw from her alike the approving speech, or blush, at least.

She seems very likely in love with nature, life, and small kindesses.  What made him mad was the fact that she ranked his approval for her with everything else--sunsets, cherries that someone brought her, riding her mule.  How dare she!  (Smile)

What a wonderful poem!  In the poem, the Duke of Ferrarra, a place in Italy, is speaking to an emissary (spokesperson).  The emissary works for a man whose daughter is to be engaged to the Duke.  The Duke is showing the emissary a portrait of his last wife.  He talks about the qualities of the Duchess as they look at the picture.  Appartently, the Duchess was flirtatious in nature.  She has a blush upon her cheek that he believes is part evidence of her flirtation with the painter himself.  He explains that everyone was equally likely to receive attention from her.  He is obviously angered by this.  He says that the Duchess showed a lack of respect for position - the Duke's name and nobility should have guaranteed that she show more attention to him than anyone else.

The Duke explains that he tried to stop her behavior, which demonstrates his need to control her; however, his attempts met deaf ears.  So, he had to stop the behavior himself.  We don't know how he did so, but there is a suggestion that he ordered her death.

As the poem wraps up, the Duke suggests they again discuss the upcoming marriage.  It would seem that the Duke's explanation of the portrait could serve as a warning for the emissary to bring back to his lord and the new bride - behave, or face the consequences!

In Robert Browning's poem "My Last Duchess," Browning describes a duke who is speaking to the representative of a future wife for himself.  This duke, as a sort of warning to the representative of his bride, shows the painting of his previous spouse, now deceased, and describes what he believes to have been her weak and flirtatious character.  In doing so, he is able to convey the message of warning that his new wife had better be better behaved, or else.

In lines 12-19, he mentions that the representative might have noticed the coy and excited expression on the former wife's face in the painting.  The duke says that many have wondered and asked that question, and that it wasn't her husband alone that made her appear to be so happy.  Rather, she seemed to give delighted glances to a lot of people, for a lot of reasons.  For example, the painter of the painting (Fra Pandolf) might have told her that part of the mantle in the painting was covering too much of her wrist, or that he was incapable of painting the flush of color along her throat.  These little things that people said to her often made her blush with joy.  The rest of the poem goes on to indicate that the duke highly disapproved of his wife's joyous behavior; he considered it inapproprate that she should be happy around anyone other than him.  So, he "gave commands," and the wife, the reader has to assume, was killed.  This was to warn his future bride that she had beeter not behave that way.

A bit bizarre, yes, but it certainly makes for an entertaining story for a poem.  I hope that helped a bit; good luck!