Jemmy the Cat serves as the prince's pet. He displays instant hostility toward Marina when she arrives in the human world, viewing her as a threat. Jemmy repeatedly plots to eliminate her, including by summoning a pack of wolves to attack her. He possesses the ability to communicate with humans, though the specifics remain undefined. Motivated by jealousy, Jemmy actively sabotages the relationship between Marina and the prince. He eavesdrops on their private conversations and reports details to the prince's parents to undermine Marina. Specifically, he informs the king and queen of the prince's intention to marry Marina instead of their chosen princess. This interference directly contributes to the royal family separating Marina from the prince and arranging his marriage to the Princess of Suomi. Jemmy's actions successfully remove Marina from the prince's life. He faces no repercussions for these deeds, achieving his goal despite the destructive outcome for Marina. His role is limited to these events within the film, with no further background, development, or appearances in other media indicated.