TV-Series
Description
Bertholdt Hoover, an Eldian from Liberio's internment zone in Marley, became one of Marley's Warriors. Witnessing Porco Galliard bully Reiner Braun as a child, he intervened, helping Reiner up and forging a lifelong bond. This act secured his selection as a Warrior candidate, leading him to inherit the Colossal Titan's power, which he rapidly mastered.

In 845, Bertholdt infiltrated Paradis Island with fellow Warriors Reiner Braun, Annie Leonhart, and Marcel Galliard to reclaim the Founding Titan. Approaching Wall Maria, they encountered Ymir's mindless Titan. When it attacked and nearly killed Reiner, Marcel sacrificed himself. Bertholdt reportedly fled in terror during the attack. Regrouping later, they proceeded with their mission under Reiner's leadership despite initial hesitations. Standing before Wall Maria, Bertholdt questioned his ability to destroy the structure before transforming into the Colossal Titan and breaching Shiganshina District's gate. This caused widespread destruction, allowing Titans to flood in and leading to Wall Maria's fall. Bertholdt, Reiner, and Annie then posed as refugees from a mountain village south of Wall Maria, forging family records. For two years, Bertholdt and Reiner worked as lumberjacks while Annie gathered intelligence within Wall Sheena.

Bertholdt later enlisted in the 104th Cadet Corps alongside Reiner and Annie. Commandant Keith Shadis noted his great potential but criticized his utter lack of initiative and self-confidence. He graduated ranked 3rd in his class. Early in training, he and Reiner advised Eren Jaeger struggling with defective vertical maneuvering gear. Bertholdt expressed a desire to join the Military Police for safety, encouraged by Eren citing the trauma of Shiganshina's attack. Frequently described as taciturn, nervously sweating, and withdrawn, Bertholdt often stayed in the background. He identified himself as a coward with weak willpower, tending to follow others. This passivity manifested during Marco Bott's death; he panicked, showed visible distress, but took no decisive action, later allowing Reiner to assign responsibility to Annie due to Bertholdt's perceived unreliability. Despite his reserved nature, he displayed fierce protectiveness when Reiner or Annie were threatened, such as brandishing his blade at Armin Arlert over concerns about Annie being tortured and reverting to Marleyan propaganda about humanity being "children of the devil."

Five years after Shiganshina's fall, Bertholdt transformed again at Trost District, breaching its gate. He participated in Eren Jaeger and Ymir's abduction, revealing his identity as the Colossal Titan. Conflicted when confronted about his friendship with the 104th cadets, he called them "precious comrades" while maintaining his mission's necessity. His personality shifted significantly during the Battle of Shiganshina, becoming detached, indifferent, and coldly resolved. He calmly declared his intent to kill his former comrades, remained unfazed by Armin's psychological tactics invoking Annie, and expressed disappointment when his transformation failed to eliminate all Scouts. He rationalized his actions by accepting the world's inherent cruelty, stating no one was at fault. Despite this resolve, Bertholdt harbored an intense terror of Pure Titans and personal death. When captured and approached by Armin's Pure Titan, he abandoned his composure, desperately begging his former friends for help and screaming for Reiner and Annie before being devoured alive. After his death, the Colossal Titan's power transferred to Armin Arlelt.

Bertholdt's character development culminated in a pivotal moment where he overcame his passivity. Reflecting on the suffering caused to Reiner, Annie, and humanity during Marco's death, he resolved to prevent further pain to his loved ones. He asserted his determination to act independently, surprising both Zeke Yeager and Reiner, who had previously considered him unreliable. This shift established his core motivation: ensuring those he cared about would never endure such suffering again.