Season 1, often called the "Prologue," is a brutal exploration of the Viking Age. While it begins as a standard revenge story—Thorfinn seeking to kill Askeladd for murdering his father, Thors—it quickly subverts that trope. Thorfinn becomes a slave to his own hatred, losing his childhood and humanity in the process. The "villain," Askeladd, ironically becomes Thorfinn’s mentor, showing that in a world of war, there are no pure heroes or villains, only survivors.
To satisfy the complete1to part of your keyword, here is the full episode list for Vinland Saga Season 1. Each title hints at the episode’s thematic core.