Sven is Kristoff's reindeer and close friend. The two were adopted and raised by the trolls. Sven is incredibly loyal to Kristoff and, along with helping him with his business ventures, serves as the ice harvester's conscience. To this end, Sven urged Kristoff to accompany Anna on her journey and later helped the ice harvester realize his growing affection for the princess.
When he was a fawn, Sven was rescued by Kristoff. Following this incident, the two became friends and worked together to mine ice alongside the older ice harvesters. One night, as they were leaving the ice fields, Sven and Kristoff noticed two horses and their riders rushing past; transfixed by the ice trail being left behind, Kristoff mounted Sven in the hopes of following the trail. The pair eventually reached the Valley of the Living Rock.
At the valley, Sven attempted to get a better look at the riders, but Kristoff promptly pulled him behind a rock so as to remain hidden. As they observed the figures, rocks began to roll towards the riders, revealing themselves as trolls. Though Kristoff expressed surprise, Sven appeared intrigued by the burst of activity. Suddenly, the rock in front of the pair burst to life, revealing a female troll, Bulda. Sven gave the troll a friendly sniff and lick, after which she addressed the pair as "cuties" and stated her intent to adopt them.
True to her word, Bulda took in Kristoff and Sven; in the years that passed, Sven grew closer to Kristoff, who would often simulate the reindeer's voice to "converse" with him.
Thirteen years later, Sven and Kristoff were in the village on the day of Elsa's coronation. However, they did not stay for long and instead set out to harvest more ice. After Elsa cast her winter spell, Sven and Kristoff headed to Wandering Oaken's Trading Post and Sauna to purchase supplies for the sudden winter weather.
After Sven witnessed Kristoff being thrown out of the store by its burly owner, Oaken, the empty-handed ice harvester sadly informed the reindeer that he was unable to purchase the carrots. Though Sven was disappointed, Kristoff optimistically pointed out that they had a place to stay for the night: a barn located near Oaken's store.
While the ice harvester and reindeer settled down for the night, a young woman, Anna, interrupted them and asked for Kristoff's help in going to the North Mountain. Though Kristoff refused, he reconsidered when Anna offered him the supplies and carrots he was unable afford. That night, the three set off for the North Mountain using Kristoff's sled. Sven raced through through the forest until Kristoff suddenly brought the reindeer to a stop while he surveyed their surroundings. When Kristoff spotted wolves emerging from the treeline, he ordered Sven to move.
Despite the reindeer's efforts, the wolves continued to gain ground, and the trio rapidly approached a gorge. Kristoff threw Anna onto Sven's back and told him to jump after separating the sled from the reindeer's harness. Though Sven and Anna made it to the other side, Kristoff landed in a precarious location and began to slip down the cliff. However, Anna threw a hatchet tied to a rope that was fastened to Sven, and the two of them pulled the ice harvester to safety. Lamenting over the loss of his sled, Kristoff almost forsook Anna; however, after Sven and the ice harvester had a "discussion" about Anna perishing without help, Kristoff decided to press onwards.
With no other option, Sven, Kristoff, and Anna were forced to continue to the North Mountain on foot. Their journey took them through a frozen forest, where they were entranced by the beauty of the ice crystals; Sven took particular notice of how the frozen droplets on the trees produced a chiming sound when rattled. However, the trio soon realized there was another presence in the forest, a snowman named Olaf. Though Anna and Kristoff were initially surprised by the living snowman, they gradually grew comfortable around him. Sven was especially interested in the new carrot nose that Anna had given Olaf, though his attempt to eat it failed. When Olaf stated he could lead them to Elsa so that she could restore summer, Sven and his human companions followed the snowman's lead.
The ice palace
With Olaf's help, the four approached Elsa's ice palace and prepared to ascend an ice staircase over to the palace doors. However, Sven was unable to find traction on the steps, and Kristoff told him to wait at the bottom of the staircase while he and the others proceeded, to which Sven obediently complied.
As he waited for the others, Sven went to lick the staircase but ended up having his tongue stuck to the frozen surface. Not long after, a hulking snowman, Marshmallow, burst through the palace doors and threw Anna, Kristoff, and Olaf out. While Anna went to confront Marshmallow for his actions, agitating the snowman in the process, Sven managed to extricate himself from the staircase and ran down the mountain independent of his companions. The group finally reunited at the base of the mountain, where Olaf happily greeted Sven, who tried once again to eat the snowman's nose. After Kristoff realized Anna's hair was turning white due to being struck by Elsa, the four hastened to find a cure.
Race against time
By nightfall, the group approached the Valley of the Living Rock; while Anna and Kristoff walked behind, Sven carried Olaf on his back, from which the snowman pointed out the aurora borealis. The four gradually reached a clearing, and while Kristoff gestured around at the trolls, who were still in their rock forms, Sven enthusiastically awaited for the trolls to burst to life.
The trolls eventually revealed themselves, and upon seeing Anna, they attempted to set her up with Kristoff. However, the princess collapsed from her curse, and after Pabbie informed her that "only an act of true love" could save her, Sven took his companions on his back and swiftly departed for Arendelle.
On the approach to Arendelle, Olaf broke from the group while Sven continued on towards the castle. At the gates, Kristoff dismounted Sven and gave Anna to Kai and two handmaids, after which the gates closed on him, cutting his view of Anna. Though Kristoff stared momentarily at the gates with worry, he merely sighed before walking away; Sven, however, was more reluctant and brayed in concern before turning to follow his friend.
As the two traveled further from the castle, Sven continued to lag behind Kristoff. However, with sudden resolve, Sven spurred forward and blocked Kristoff's path while snorting and grunting. When the ice harverser asked what was wrong, Sven proceeded to nudge his friend with his antlers, to the former's annoyance. Unrelenting, the reindeer produced a series of snorts and brays, but Kristoff continued to ignore him, stating he could not understand when the reindeer spoke in that manner.
Though Kristoff tried to walk around him, Sven used his antlers to pick Kristoff up, intent on carrying him back to Anna. But Kristoff managed to escape and, above Sven's continued grunts, adamantly stated that they were not going back, as Anna was "with her true love." At this, Sven glanced at Kristoff with disbelief, but before they could discuss the matter further, a sudden gust of wind drew the ice harvester's attention back to Arendelle; seeing a winter storm forming above the castle, Kristoff realized Anna was in danger and began to make his way back. Sven quickly caught up, and after Kristoff mounted the reindeer, the two sped back to Arendelle.
As the two reached the fjord, they entered into the heart of the storm and were met by the powerful winds within; however, they fought through, speeding past a multitude of ships trapped in the ice. But as Sven pressed onward, one ship began splintering apart in the ice, and the reindeer was forced to navigate through its collapsing structure. Though the pair emerged unscathed, the bow of the ship smashed into the ice, cracking the surface beneath Sven and Kristoff. Seeing a gap, Sven tried to leap over but fell short and was forced to buck Kristoff to the other side, while he fell into the freezing water. After a few moments, the reindeer burst from the water, and after clambering onto a chunk of ice, he bellowed at Kristoff to continue without him.
The Great Thaw
When the storm suddenly subsided, Sven rejoined with Kristoff and Olaf and joined them in watching Elsa grieve over her sister's frozen form. For a few moments, they joined in her sorrow; however, Anna began to thaw out, and Sven nudged his despairing friend to alert him of what was occurring. After Anna thawed out and reconciled with Elsa, the latter realized that love was the key to controlling her powers; Sven and the others watched as Elsa thawed out the kingdom, restoring summer to Arendelle. Sven and Kristoff then happily watched as Anna and Elsa embraced to reaffirm their bond.
With order restored to Arendelle, Elsa returned to her duties as queen, and along with making Kristoff the official "Arendelle Ice Master and Deliverer", she presented Sven with a medallion emblazoned with her snowflake and helped Anna provide the two with a new sled. After proudly displaying his medal and the sled to Kristoff, Sven focused his attention on Olaf, who sneezed after sniffing some purple flowers, causing his carrot nose to land in the reindeer's mouth. Sven triumphantly slurped up the carrot, to Olaf's disappointment. However, Sven had not swallowed the carrot and returned it to the snowman, who beamed and hugged the reindeer delightfully.
Later in the castle courtyard, Sven and Kristoff skated alongside Anna, Elsa, Olaf, and the villagers.
Sven has a vibrant personality and is openly friendly to those he meets, particularly if they can offer him a carrot, as shown by his exchanges with Anna and Olaf. He is extremely curious of his surroundings and does not hesitate to give things that capture his interest a nudge, sniff, or lick, such as when he explored the chiming sounds of frozen water droplets in an icy forest. Sven also attempted to lick the staircase leading to Elsa's palace after he was forced to wait outside alone.
Though he is incapable of human speech, Sven nonetheless has a keen awareness of his human companions, having convinced Kristoff to return to Arendelle, certain that Anna was not with her true love. The reindeer is also extremely devoted to those he cares about, having bucked Kristoff to safety while plunging into the frigid waters of the fjord himself. He also good-naturedly returned Olaf's carrot nose, having simply pretended to swallow it.
As a reindeer, Sven possesses both strength and stamina, traits needed to draw a sled fully loaded with ice. He has the strength to pull this sled at great speeds, even when it is loaded with passengers and supplies; he is capable of sustaining his pace for a considerable duration, able to pull Kristoff's sled uphill while simultaneously outpacing a pack of ravenous wolves. Sven was even able to successfully launch himself across a large gap while carrying Anna upon his back, and later, he was able to lift Kristoff using just his head.
- Main article: Sven's relationships
- Olaf & Sven on Thin Ice
- Sven appears alongside Olaf in Frozen's teaser trailer.
- Sven appears in the fourth season of the ABC show, Once Upon a Time.