Askeladd was the son of a Welsh princess and the bastard son of a Danish warrior who took his mother away from her homeland. Growing up in misfortune, He plotted and succeeded in killing his father, his father's family and other children after seeing his mother go insane from suffering under his father.
Several years later, Askeladd becomes the leader of a group of Danish pirates who have no knowledge of his Welsh lineage and is seen being hired by the Jomsviking commander, Floki, to assassinate a former Jomsviking who deserted the army known as Thors.
During his initial ambush on Thor's crew, who were on their way to join the Jomsviking army, Askeladd and his crew are shocked to see that Thors was capable of defeating several of Askeladd's men with his bare hands. Thors then proposes to Askeladd that if the former could defeat the latter, Askeladd would allow Thors' crew to leave. Askeladd also reveals to Thors that Floki was the one that sent him assassinate Thors via his scent. The two then engage in a duel, with Askeladd attempting to defeat Thors by using his speed and the environment but is tricked and overwhelmed by Thors' skill and tactical mindset.
Askeladd then asks Thors to be the leader of his crew when Thors reveals that he wanted to live a life that required him to no longer commit violence but goes back on his word to keep face when his crew is shocked by his request. This angers Bjorn, Askeladd's right hand man who was easily defeated by Thors earlier, who then holds Thors' son, Thorfinn, at ransom. Thors then reminds Askeladd that Askeladd agreed to let Thors' crew go if he won the duel and Askeladd hesitantly agrees to let go of Thors' crew and orders his men to shoot down Thors. One of Thors' men tries to attack Askeladd but is easily defeated by him. Askeladd then tells Thors' men to not dishonor Thor by reminding them to stop foolishly throwing their lives away in a fight against him.
Hours later, a ferocious Thorfinn stays behind on a rowboat going after Askeladd's ship while repeatedly threatening to kill Askeladd for killing Thors. This catches the attention of Askeladd and his crew but they dismiss Thorfinn's presence and leaves him to die.
Years later, Askeladd has adopted Thorfinn into his crew and exploits the youth's skill in combat to work for him during his heists while Thorfinn repeatedly challenges him in duels that Askeladd continues to win due to Thorfinn's short temper and predictability in combat.