Hans is one of the princes of The Southern Isles and one of the villains imprisoned in the Isle of the Lost.
Before the Isle of the Lost
Once the Southern Isles is given word of Queen Elsa's coronation, Hans is the royal representative that attends in honor of his kingdom. Along with the other invited royalty, Hans arrives on the day of the event and is first seen arriving in Arendelle on his horse Sitron, accidentally running into Princess Anna. Using grace and charm, Hans immediately woos the lovesick princess, with Anna almost immediately falling for him due to his wondrous looks and undeniable charisma. Their little flirtation is cut to a close, however, when the bells for the queen's coronation are rung. As Anna runs off, Hans realizes he's found the perfect tool for his plot to domination. Moments later, Hans attends Queen Elsa's crowning, waving to Anna as he watches alongside the other visiting royals and dignitaries. Later on that night, a ball is held in honor of the new queen, and Hans appears at the celebration party, soon finding and inviting Anna for a romantic waltz after "coincidentally" bumping into her once again.
The romantic dance eventually leads to an entire "date", with the entire night of the young couple being spent "bonding". During their time together, Hans learns of Anna's longing of having someone special in her life, with her sister, apparently developing a dislike of her, to which Hans openly relates to, only furthering Anna's connection with him. And with this, Hans promises to never shut Anna out, unlike Elsa, much to the princess's absolute joy. By the end of their tour throughout the kingdom, Hans works up the courage to propose, with Anna agreeing in a heartbeat. The two head back to the royal throne room, where the party is being held, to ask for Queen Elsa's blessing, to which Elsa coldly refuses, stating that Anna should not be marrying someone she just met, ending the party and ordering Hans to leave out of frustration. Heartbroken, Anna confronts her sister, but this causes the queen's powers over ice and snow (the reason she goes so far out of her way to isolate herself from the outside world) to be revealed, much to Hans' surprise.
The Duke of Weselton, one of the neighboring royals, immediately declares Elsa a monster, and orders his men to capture her. Elsa flees, accidentally causing an eternal winter over Arendelle while doing so, having Anna and Hans chase after her until she is out of reach. Hans asks Anna if she had known of Elsa's mysterious abilities, to which the princess denies. In order to save the land, Anna volunteers to go after Elsa, but Hans was not too fond of the idea, knowing if something terrible should befall Anna, his quest for domination would be abolished, as they still were not married just yet. However, Anna insists that Hans stays behind to rule during her absence, to which the prince immediately agrees to.
It wasn't long before Arendelle became an icy wasteland, with citizens becoming weak due to the frigid temperatures, causing mild chaos throughout the land. Hans took advantage of the situation to endear himself to the people, serving as a dependable ruler, offering blankets and care packages to the villagers. The Duke of Weselton soon arrived and scolds Hans for his actions, believing the kingdom's attention should be focused on taking action against Elsa in order to end the curse, as opposed to "giving away all of Arendelle's tradable goods". When Hans reiterates Anna's specific orders, he's met with more suspicion from the Duke, who openly believes Anna to be conspiring with Elsa to doom the land, which angers Hans to the point of threatening the Duke with arrest for treason against the crown. Suddenly, Anna's horse rushes into the city, unattended and in a panic. Hans is able to calm the animal and quickly gathers that Anna's absence is a sign of danger. Needing either Anna or Elsa in order to complete his plot, Hans calls forth an army of volunteers to travel into the mountains in search of the princess and queen. In hope that Hans and his search party will encounter Elsa during their journey, the Duke volunteers his two bodyguards to join the expedition, secretly ordering them to kill Elsa when encountered, believing her death to be the key to ending the eternal winter.
Hours after their departure from Arendelle, Hans and his army find Elsa's ice palace, and are almost instantly attacked by the fortress' guardian, Marshmallow. Hans and his army battle against the beast, though he proves to be nearly invincible and completely implacable. Fortunately for the prince, he is able to get a clear path at the snow beast and slices Marshmallow's left leg clean off, causing the creature to stumble into a chasm to his apparent death. With him out of the way, Hans and the others rush inside to find Anna, but she is nowhere in sight. Instead, they find Elsa seconds away from killing the Duke's two guards who had previously snuck past Marshmallow on orders of the corrupt Weselton representative. Hans is able to stop her from killing them as they intended for her, freeing the two thugs. However, one of the thugs attempts to strike her with their crossbow, but Hans interferes and, with apparent purpose, causes the bolt to shoot upward to Elsa's massive chandelier. The chandelier comes crashing down, and the impact manages to knock Elsa unconscious.
Captured, Elsa is imprisoned in Arendelle's dungeon. With the winter curse spiraling out of all control, Hans knows he must find a way to save his potential kingdom and decides to pay Elsa a visit, maintaining the ruse that he's out for her best interest. He pleads for her to put an end to the winter and bring back summer, but Elsa confesses that she doesn't know how, and begs to be released in hopes that leaving will draw the storms away with her. Hans claims he will "do what he can", and returns to the Duke of Weselton and the other dignitaries in the library.
Now that he knows Elsa doesn't know how to lift the curse, her life and favor are worthless to Hans. He makes the decision to head back into the mountains to search further for Anna, still needing her marriage in order to legitimize his hold on the throne. The assembled dignitaries, however, advise against the prince's decision; they voice the fact that should Anna fail to return, Hans is the only individual eligible to assume control of Arendelle. Unfortunately for Hans, Anna is suddenly brought into the room by the castle servants—weak, cold and white-haired, desperately begging the prince for a kiss. The two are given privacy as Anna explains that, during her journey, Elsa froze her heart, and only an act of true love can save her from freezing to death. However, with circumstances having changed dramatically, Hans only smirks and rejects Anna, moving to extinguish any source of heat and warmth within the room to quicken her death, while simultaneously revealing his matured plot to marry Anna and become King of Arendelle through ascension. He subsequently announces that his next move is to kill Elsa and restore summer, making him a hero in the eyes of Arendelle's citizens. Hans then leaves Anna to die, locking her within the room to prevent her from escaping and interfering.
Hans then returns to the Duke and the other dignitaries, pretending to be terribly distraught as he declares Princess Anna dead, through murder by Queen Elsa. The prince also adds that he and Anna were able to give their marriage vows before the latter's passing, thus leaving Arendelle in his hands. In their desperation, the assembled dignitaries vocally look to Hans for the next course of action for the kingdom to take, leading Hans to make his first order as ruler by charging Elsa with treason and sentencing her to death. Alongside the royal guards, Hans makes way to the dungeon, where they find Elsa's cell vacated, as she managed to escape. Furious, Hans decides to take matters into his own hands and goes into the frozen fjord to confront Elsa himself, sword in hand. He eventually does so, immediately telling her that escaping all the damage she's caused is futile. Elsa merely pleads for mercy, asking the prince to take care of her sister in her absence, to which Hans responds by informing Elsa of Anna's imminent death as a result of the former's strike to her heart, despite his "efforts" to save her; blaming Elsa for the tragedy. Devastated, Elsa falls onto her knees, with her sorrow freezing the very air around them, and providing Hans the opportunity to end her.
Before Hans is able to give the killing strike, however, Anna arrives and blocks the prince's blow, completely freezing just before the sword strikes her, thus freezing and subsequently shattering the blade with her frigid body temperature. The shockwave caused knocks the evil prince off his feet, upon the ice, and rendering him briefly unconscious.
Following Hans' downfall, Elsa discovers the means necessary to undo her eternal winter, and immediately does so, leaving Arendelle thawed and peace within the kingdom restored. As Hans finally regains consciousness and struggles to his feet, Anna's traveling companion, Kristoff, moves in to pummel him, though he is stopped in his tracks by the princess, who makes the decision to confront Hans herself. The sight of Anna alive confuses Hans, prompting him to ask how she had survived the frozen heart curse -- the princess responds by declaring Hans is the only individual present with a "frozen heart", and satisfyingly begins to take her leave, before suddenly turning her heel and punching the traitorous prince in the face, causing him to fall off the ship they were aboard, and into the waters of the fjord. Humiliated and defeated, Hans is arrested and caged aboard the brig of a French ship by the royal guards. The French dignitary aboard the ship assures Arendelle's government that Hans will be returned to the Southern Isles, where he will face an unspecified punishment at the hands of his brothers.