Atli, a former warrior in Askeladd’s mercenary band and loyal brother to Torgrim, first appears with short light blonde hair, a mustache, and piercing green eyes. After a time skip, his look shifts to longer hair tied back, a bear pelt scarf, and a teal outfit. Though sharing Torgrim’s contempt for Christianity, their unbreakable bond and mutual trust anchor their camaraderie within the group, forged through years of partnership.

Among the few survivors of the internal strife following the clash with Thorkell, Atli remains alongside Askeladd, Bjorn, Thorfinn, and Torgrim. Granted freedom by Askeladd on the condition of abandoning warfare, he and his brother attempt a peaceful life, though danger shadows their steps.

Captured during the Baltic Sea War arc by Vagn’s forces, Atli cracks under interrogation, exposing Floki’s orchestration of Thors’ assassination, Askeladd’s complicity, and Thorfinn’s true identity—intel Vagn exploits to hunt Thorfinn. This moment lays bare Atli’s fragility outside mercenary life and his unintended ripple effect on unfolding conflicts.

Despite efforts to renounce violence, retaliation finds him: Thorkell executes Atli, a brutal end underscoring the inescapable cycle of vengeance and the weight of past deeds.

His presence spans manga chapters and anime episodes, with the adaptation expanding his role to replace faceless characters. Key arcs trace his survival of betrayals, pivotal battles, and eventual capture—a catalyst exposing Floki’s schemes and propelling Thorfinn’s journey.