Born March 30th in Shiganshina District to Grisha and Carla Yeager, Eren Yeager witnessed his mother's death during Wall Maria's fall. This trauma ignited an intense hatred for Titans and a desperate desire for freedom beyond the walls, forging a hardheaded, impulsive, and vengeful personality driven by black-and-white morality that justified extreme violence against oppressors. Demonstrating a fierce protective instinct as a child, Eren killed Mikasa Ackerman's captors to rescue her, leading her to join the Yeager household as his adoptive sister. Armin Arlert's book fueled Eren's curiosity about the outside world and disdain for those content within the walls. He joined the 104th Training Corps alongside Mikasa and Armin, graduating fifth. During the Battle of Trost District, after being swallowed by a Titan, Eren triggered his first transformation into the 15-meter Attack Titan—a power inherited from his father via Titan serum, granting injury regeneration and self-transformation through purposeful self-harm. Eren later inherited the Founding Titan following his father's murder of the Reiss family. Discovering Reiner Braun and Bertholdt Hoover as the Armored and Colossal Titans responsible for his mother's death during the Clash of the Titans arc deepened his trauma and moral conflict. Confronting the Smiling Titan unlocked the Founding Titan's coordinate ability, allowing him to command nearby Titans to devour it. Reaching his father's basement revealed the truth: Titans were transformed humans and Eldia faced oppression by Marley. This shifted Eren's enemy from Titans to humanity beyond Paradis Island. In 854, Eren infiltrated Marley undercover, growing long hair and a goatee while wearing an Eldian armband. During the Raid on Liberio, he consumed Lara Tybur to gain the War Hammer Titan, initiating war by massacring civilians, marking his transition into moral ambiguity. He orchestrated a coup with the Yeagerist faction, manipulating events to ensure his friends became heroes by opposing him, provoking Mikasa and Armin to sever ties and feigning indifference toward their feelings. Contact with Ymir Fritz in the Paths dimension granted Eren the Founding Titan's full power. He manipulated his father's memories to ensure the Reiss family's murder, revealing his ability to perceive past and future simultaneously. This temporal awareness compelled him to initiate the Rumbling—activating Wall Titans to destroy all life beyond Paradis—as the only path to his friends' freedom. His Founding Titan manifested as a colossal skeletal structure with a detached head connected by vertebrae, moving via undulating ribs. Mentally regressing to a childlike state to cope with the genocide, he expressed anguish to Armin about the inevitability of his actions and his desire for Mikasa's happiness. By the final conflicts, his appearance featured shoulder-length hair tied in a bun, a clean-shaven face, and bandaged head injuries. Eren was ultimately decapitated by Mikasa, ending the Rumbling. His character arc concluded as a figure who embraced villainy to liberate Paradis, embodying themes of cyclical violence and the burdens of foresight.