The Duke of Weselton did not journey to Arendelle alone; he was accompanied by his two bodyguards and made sure to the use them to their fullest. When Elsa's powers were revealed at her coronation party, the Duke immediately retreated behind his guards in fear of the ice spikes. Later, he hid behind them again, convinced that Anna had powers similar to her sister's. He also had his guards accompany Hans to the North Mountain, demonstrating unquestionable loyalty in their attempts to kill Elsa on the Duke's orders.
The Duke of Weselton was often at odds with Hans, starting with an initial confrontation regarding Anna and Elsa; though the Duke was convinced that Anna was a "monster" like Elsa and that the latter tried to kill him, Hans defended the princess and queen. Tensions between them escalated during Hans' time as interim leader of Arendelle; the Duke protested Hans' giving away of the kingdom's tradable goods and told him that his trust in Anna was misguided due to her relationship with Elsa. However, the Duke stopped his tirade after Hans stated his willingness to defend Arendelle from treason.
Despite these conflicts, the Duke expressed shock when Hans stated that Elsa had killed her sister, and he firmly advocated action to stop her.
The Duke of Weselton encountered Anna at Elsa's coronation party; after the queen declined a dance, the Duke settled instead for Anna. During his dancing, he tried to pry knowledge of Arendelle's isolation from Anna, but after the princess stated that she did not know, the Duke gave up the effort. The two continued dancing for a few more moments before the Duke allowed Anna to return back to Elsa's side.
The two encountered each other in the courtyard after Elsa exposed her powers and ran away. Frightened, the Duke hid behind his guards as Anna approached, fearing that she was a "monster" too. As he hid behind his guards, the Duke argued with Anna over Elsa's motives until the princess decided to pursue Elsa, a decision that the Duke was quick to support. Though he supported Anna's decision to search for Elsa, the Duke remained wary of the princess, citing his concerns of Anna's allegiance to Hans. However, he expressed shock when Hans revealed Anna had died by Elsa's hand, remarking with horror that she had been killed by "her own sister."
The Duke of Weselton sought to make an impression on Elsa to exploit Arendelle's riches and was initially polite to the queen, even offering her first dance as ruler. However, after Elsa revealed her powers, the Duke's views changed dramatically, and he was quick to denounce the queen as a wicked sorceress. When Elsa fled the Great Hall, the Duke pursued her out to the courtyard and called for the queen to be stopped. This prompted Elsa to blast the Duke with her powers, causing him to slip to the ground, where he declared her to be a "monster". After Elsa fled Arendelle and cast a winter spell upon the kingdom, the Duke descended into hysterics, saying the queen had "cursed this land" and ordered his guards pursue her. He revealed the full extent of his fright when he argued with Anna, insisting that Elsa had tried to "kill [him]."
The Duke remained frightened of Elsa during the winter; after Hans asked for volunteers to help him find Anna, the Duke was quick to seize the opportunity to volunteer his two guards. Acting on his fears, the Duke gave them secret instructions to kill the queen if they encountered her, hoping to put an end to the winter. This attempt on Elsa's life was unsuccessful, but when Hans revealed that the queen had killed her sister, the Duke declared that she was undoubtedly a monster and advocated decisive action to be taken against her.
After Elsa thawed Arendelle, the Duke was upset upon hearing that the queen had cut ties with his kingdom.