Thorfinn (トルフィン, Torufin), also nicknamed Karlsefni, is the protagonist of Vinland Saga. A former warrior in Askeladd's band, he is the son of Thors, the most renowned Jomsviking warrior until his defection. Thorfinn is related to the leadership of the Jomsvikings through his mother Helga, who is chief Sigvaldi's daughter and Thorkell's niece.
After attacking Canute in a rage when the latter killed Askeladd, Thorfinn's goal for most of his life, Thorfinn was enslaved as punishment. Four years later he gained his freedom and changed his life. He is currently a traveling merchant working with Leif Ericson and attempting to colonize Vinland.
In the first chapter and later in the manga, Thorfinn's appearance largely stayed the same: Bushy hair, old clothes, two knives and a rebellious, angry face. Later on, we see Thorfinn from his childhood, when he lived in Iceland. He had a happier face, round with bright, curious eyes, and nice hair.
When the series begins, Thorfinn is shown as an innocent and friendly boy who is searching for adventure. He shared a very good relationship with his family and enjoyed stories told by Leif about his adventures. He has a good relationship with his father and looked up to him immensely, shown when he decides to follow Thor's by sneaking on his boat to follow him. This would become the foundation of Thorfinn's drive to avenge his father.
However when he joins Askeladd's band, he has shown to become a cold blooded individual, hellbent on his goal to avenge his father. He becomes cold toward others, unmoved by and uninterested in what they do or think of him, choosing instead to keep to himself, as shown ignoring the invitations from his fellow vikings to join in on the fun as well as ignoring to eat dinner with the rest of them.
His flaws lie in his temper and impulsive nature. Choosing to ignore Askeladd's input despite the benefits it may be able to bring him which lead to him loosing fights against Askeladd. This leads to him making extremely reckless decisions from failing to think things through and such actions lead to him suffering. Though possessing talent far beyond the norm for his age, however his hot-headed attitude is his biggest weakness.
"No he is the real thing, for sure. A fighter that agile is rare to come across...." --Garm
Overall Abilities: Thorfinn grew up on the battlefield, having been exposed to it following his father's death thus he is noted to have a wealth of battle experience. Hence he grew into a highly skilled warrior capable of swiftly killing warriors at least twice his age. As Thorfinn's fight style plays focus on striking vital points instead of clashing with blades directly, he has developed a nimble style which plays emphasis on speed. Thorfinn's strength is recognized by fighters such as Thorkell the tall stating he was capable to being the next head of the Jomsvikings.
Dual wield: Thorfinn's fighting style emphasizes speed combined with the dual wield of two knives, one of which was formerly owned by Thors. By targeting his opponents' weak points and taking advantage of his speed, he could typically finish off an opponent swiftly while avoiding their attacks.
Knife throwing: Thorfinn was also able to effectively use throwing knives, although they were not his primary weapon.
Enhanced durability: Although he did not engage in unarmed combat, Thorfinn had learned how to take solid hits if he was prepared. This ability noted when he withstood 100 blows from Drott to earn the right to speak to Canute. However when set upon by Ylfa in a rage, he was completely unprepared and was knocked out.
Enhanced Agility: Thorfinn's agility is amongst the fastest in the series, he is capable of evading from a platoon of soldiers within seconds on a battlefield, as well as scale a wall of a fortress, including jumping over a moat. In combat, he can use his agility to strike from an angle where he may finish his opponent and to find his balance quickly after taking a hit or dodging.
Enhanced Speed and Reflexes: Thorfinn's speed is regarded as his primary asset in combat. During the invasion of London he earned Thorkell's praise despite loosing to him in combat. His reflexes has enabled him to dodge and react to surprises attacks such as Snake's drawing attack however he could not dodge Garm's spear. Despite Garm proving faster than him as well as wounding Thorfinn, Thorfinn was nonetheless able to dodge his movements with his eyes. At Jomsburg, he was able to cover a distance of several meters before his pursuers could notice he had ran away from them. A testament to Thorfinn's reflexes is shown when he was acknowledged by Garm as being the the only fighter he has met to dodge his spear so quickly.
He lived with his family and was a happy and a lively boy. He played with the children in the village especially in mock combat with a wooden sword and shield, even though he was always one of the first to be beaten. One day Floki, and his Jomsviking crew come to Iceland to get aid from his father,Thors. When his father was going out to a battle, Thorfinn hid himself in a barrel on his fathers ship. pirate/viking called Askeladd , who was hired by Floki to take down Thors, came and dueled Thorfinn's father. Thors took down half of Askeladd's men, including his second in command, and then the two faced off. Thors won the battle, but in exchange for thorfinn's life, he was killed by many arrows from Askeladd's men. After his father died, Thorfinn vowed to seek vengeance for his father, by becoming one of Askeladd's men and dueling him every time he completes a mission in combat, so he can avenge his fathers death in a fair battle.