Control and Confession
The duke's controlling nature becomes clearer with each revelation. When he mentions "She rode with around the terrace-all and each," we see how he confined her to a small space, denying her freedom throughout their marriage.
His jealousy intensifies as he complains, "Whene'er I passed her; but who passed without Much the same smile?" Here, the duke practically accuses his deceased wife of infidelity simply because she smiled at others. This paranoid jealousy reveals his inability to control "every last part of her."
The most chilling moment comes when he admits: "I gave commands; then all smiles stopped together. There she stands As if alive." This is the closest the duke comes to confessing murder, showing how he believes he has ultimate power over her. The repetition of "As if alive" creates a cyclical structure, trapping the duchess in his narrative forever.
Think about this: The duke's comparison to "Neptune... taming a sea-horse" reveals how he views his roleโa powerful god controlling a small, harmless creature. This metaphor perfectly captures the disturbing power imbalance in their relationship.