It also mentions the beauty of the poisons and the death and how the narrator wants to see the woman painfully die in front of her husband. This links to Macbeth as they find the preparation of the person’s death as well as the final act of killing them, a big thrill. The idea of pain and terror excites them and they feel that what they are doing is for the 'greater good' of themselves so to say. In both texts, they are thinking of death as a way to seek revenge and achieve their own dreams, by getting rid of the people who have the power and/or opportunity to stop them. They think of death as a bit of game-easy to commit but they do not think of the consequences that will occur from their actions, they are driven by jealousy and greed. They are desperate for attention and simply want to grab what they believe to be theirs. Lady Macbeths mention of the supernatural shows how desperate she is for her desire as she craves to possess characteristics of a man, desire for power, but the lengths she is willing go to achieve it.
Starting, Robert Browning emits a paranoid persona in the lady using repetition. He uses 'they' abundantly in the second stanza to show she is obsessed with what others [they] think of her. She can't think about anything else and is in rapt with other people's perceptions of her life. She then says they 'laugh laugh' at her, again suggesting a paranoid persona who will interpret anything around her as negative attitudes towards her. She believes she is being mocked by 'they' and everyone else around her. She has no trust whatsoever and utter embarrassment is forced upon her and consequently she is forced to act
She has fulfilled her desire (Macbeth is king), but the fulfillment has brought no contentment. She's figuratively spent herself, but achieved nothing for her efforts. Any joy she feels is contaminated.