Hvitsak was born in the four year gap between Season 2 Episode 1 and 2. Hvitserk is often seen alongside his brother Ubbe, and likely looks up to him. Ubbe flees with Aslaug, Hvitserk, Rollo, Siggy and Helga after Jarl Borg invades Kattegatte. Ragnar eventually returns from England where he is reunited with his family and with the assistance of Lagetha, he takes back Kattegatte.
An older Hvitserk is still seen playing with his brother Hvitserk and Siguard. One day while Aslug is away and Siggy is watching them Ubbe and Hvitserk wander off onto a frozen lake but Siggy pursues them. She calls out to them despite them knowing she is there Ubbe and Hvitserk ignore her. The ice breaks and Ubbe and Hvitserk fall in. They bothe nearly drown but Siggy dives in and saves them with the help of Harbard but at the cost of Siggy's life and she drowns.
Ubbe and Hvitserk receive their arm rings from their father so that they can come to Paris with him but not to fight. The Franks then attack the viking camp but Ubbe and the others manage to escape but Helga is previously wounded. After the Vikings defeat at the hands of Rollo and the Franks Ubbe returns to Kattegatte with the broken and defeated Viking army.
Ten years later after Ragnar disappeared Hvitserk has grown up into a strong and skilled warrior as have all of Ragnar's sons. Having grown up without his father present, Hvitserk has grown resentful and angry at Ragnar. Bjorn brings the news that the vikings settlement in Wessex was destroyed to his brothers. Hvitserk and his brother discuss why Ragnar didn't tell anyone. Hvitserk then says that if their father ever returned he would kill him, which Siguard agrees. Ivar gets angry at his brothers for insulting their father and refers them as "christians" calling them soft. Ragnar then returns to Kattegatte after a long absence, a broken man. He then reunites with his sons after ten long years and challenges his sons to kill him (especially Ubbe) so that they can become king. Ragnar provokes Hvitserk to kill him and screams at him to kill him but Hvitserk doesn't move.
None of Ragnar's sons step forward to challenge their father except for Ubbe but instead they just embrace. Ragnar and his sons discuss the lost Wessex settlement and why he came back. Ragnar asks his sons to come to England with him. Hvitserk refuses saying he is sailing with Bjorn to the Mediterranean sea with him, Harald and Halfdan and Floki. Once Floki's ships are ready Hvitserk travels to Frankia where they try to bargain with his uncle Rollo, who is the Duke Normandy to let them past his coastline so they can travel to the Mediterranean without any trouble. Hvitserk is introduced to his cousins William, Marcellus and Celsa. However they are imprisoned, But Rollo agrees to let them through as long as he accompanies them. They reluctantly let Rollo come due to his betrayal years earlier but not before knee hauling him for his betrayal.
Hvitserk, Bjorn, Harald, Halfdan, Floki and Rollo then sail down the Mediterranean and arrive at a town which would be later known as Spain and slaughter any resistance and steal any treasure they could get there hands on. While staring out to the ocean on a cliff Odin himself tapproachs Hvitserk and Bjorn and tells them their father is dead. Hvitserk and Bjorn return to Kattegatte, but not before dropping Rollo back at Frankia. Hvitserk then returns home and finds out that Ubbe has freed Magathe, their lover and is marrying her to his delight and asks Ubbe make sure he doesn't keep her all to himself. After the marriage ceremony Ubbe says that he and Hvitserk can share Magathe since they both love her. Hvitserk, Ubbe and Siguard then discuss their mothers death but Hvitserk says they shouldn't kill Lathe because he and Ubbe fell through the ice because of her neglect. Ubbe then says that Ivar says they should but Hvitserk says that Ivar is 'crazy'. Hvitserk and his brothers summon and form the Great Heathen Army to avenge their father. They easily defeat the forces of Northumbria and killing King Alle with a blood eagle ceremony. The Great Heathen Army then faces the force of Wessex, confusing and outmenuvering the forces and causing them to retreat. They capture King Ecbert and High Pope. Ivar demands a blood eagle for King Ecbert but Ubbe and his brother convince Ivar otherwise. Later Hvitserk watches in horror as Ivar kills Siguard by trowing an axe into his stomach. Hitserk and Ubbe look at Ivar in anger for killing his own brother, which Ivar shows no remorse.
Hvitserk will appear in this season fighting alongside his brother Ivar and Harlad
Hvitserk is often seen alongside his brother Ubbe, and likely looks up to him. Having grown up without his father present, Hvitserk has grown resentful and angry. Despite this, he is often seen laughing with his brothers, and seems to be the most lighthearted of them.
- As of the Season 2 finale, Hvitserk and his brothers would be known by the Old Norse title of Budlungr or 'prince'.
- It is often suggested that Hvitserk is the same individual as Halfdan, another name said to be the son of Ragnar. The Norse sagas name him Hvitserk, while Anglo-Saxon sources refer to a brother named Halfdan, and for this reason historians generally assume they are the same person.
- If Hvitserk is the same person as Halfdan, then he was one of the principle leaders of the Danish Mycel Heathen Here (the Great Heathen Army) and assisted with the conquests of Northumbria, East Anglia and the northern half of Mercia. Briefly, between 871-872, Halfdan/Hvitserk would occupy the city of London (then part of the kingdom of Mercia).
- The saga The Tale of Ragnar's Sons, which calls him Hvitserk, mentions that he led armies into Gardariki (the Norse term for Russia), where he lost a battle facing overwhelming odds. It claims that he was burnt alive by his captors.
- According to the saga Tale of Ragnar's Sons, Hvitserk inherited Jutland (Danish mainland) and Wendland (Luchow-Dannenberg in Lower Saxony) after the death of his father.
|Season two appearances|
|Brother's War||Invasion||Treachery||Eye For an Eye||Answers in Blood|
|Unforgiven||Blood Eagle||Boneless||The Choice||The Lord's Prayer|
|Season three appearances|
|Mercenary||The Wanderer||Warrior's Fate||Scarred||The Usurper|
|Born Again||Paris||To the Gates!||Breaking Point||The Dead|
|Season four appearances|
|A Good Treason||Kill the Queen||Mercy||Yol||Promised|
|What Might Have Been||The Profit and the Loss||Portage||Death All 'Round||The Last Ship|
|The Outsider||The Vision||Two Journeys||In the Uncertain Hour Before the Morning||All His Angels|
|Crossings||The Great Army||Revenge||On the Eve||The Reckoning|