How does Browning shape our reaction to the Duke in 'My Last Duchess'?
Our initial reaction to the Duke is formed before we've even finished reading the second line of the poem. The Duke says:
'That's my last Duchess painted on the wall,
Looking as if she were alive...'
In this line we first get a sense of how the Duke thinks of the Duchess. If he had any remotely warm feelings to her he would not have referred to her as 'his last Duchess', but by her name. We also get a hint of the Duke's possessiveness - he says 'my last Duchess'. As well as this we are told subtly that he's moving on to his next wife - 'my last duchess'. By telling us all this in the first two lines, Browning is not letting us make any mistake about what sort of person the Duke is.
It also intrigues us, and makes us want to read on, mainly because we are curious to know where the Duchess is now and what exactly she's done. We also already feel remotely sorry for her, and a little apprehensive about her fate. This is because the Duke says 'Looking as if she were alive', which can be construed as meaning two things - firstly that the duchess is still alive and the Duke is simply saying that the painting is a good likeness, or secondly, and more sinisterly, that the Duchess is dead.
In the next few lines, the Duke goes on to say that he's the only one who opens the curtain and chooses who can see the painting. He also seems to imply that the painter, Fra Pandolf, spent a little too much time with the Duchess, and is convinced that...