Eren Jaeger hailed from Shiganshina District, the southernmost settlement of Wall Maria, living there with his parents, Grisha and Carla Jaeger. This life ended in 845 when the Colossal and Armored Titans shattered the Wall, unleashing Titans into the district. During the attack, Eren watched a smiling Titan devour his mother, an event igniting his all-consuming hatred for Titans and his oath to exterminate them. Following the breach, Grisha located Eren, entrusted him with a key to the family basement, and ordered him to reclaim Wall Maria by retrieving its contents. Grisha then injected Eren with a Titan serum before disappearing, an incident Eren initially forgot. Two years later, Eren enlisted in the 104th Cadet Corps alongside Mikasa Ackermann and Armin Arlelt. He graduated fifth in his class and joined the Scout Regiment after the battle in Trost District. Eren possessed the power to transform into a 15-meter Titan, triggered by self-inflicted injury (typically biting his hand) and a clear objective. This ability, later identified as the Attack Titan, granted him immense strength, rapid regeneration, and heightened endurance. His first unintentional transformation occurred during the Trost defense after being swallowed by a Titan, saving his life and proving his potential value to humanity. His Titan form exhibited a muscular physique, elongated ears, exposed teeth, and sunken eyes, sometimes entering a berserk state under extreme stress, characterized by blackened skin and glowing blue eyes. Fierce determination, impulsiveness, and a powerful sense of justice defined Eren. He displayed intense loyalty to friends like Armin and Mikasa, frequently risking himself for their protection. As a child, Armin’s book depicting the world beyond the Walls fueled his curiosity, which evolved into scorn for those content within the Walls and deep admiration for the Scout Regiment. His lack of restraint and binary worldview often led to reckless actions, such as violently killing Mikasa’s kidnappers or charging into danger without tactical planning. Reaching his family’s basement in Shiganshina unlocked Grisha’s memories, revealing the truth about Titans, Eldia, and Marley. Eren learned he inherited both the Attack Titan and the Founding Titan from his father. The Founding Titan's power allowed control over Titans, but only through contact with a Titan of royal blood. This revelation shifted his focus from Titans to humanity across the sea, whom he identified as the true enemy. During the Raid on Liberio in 854, Eren consumed Lara Tybur, gaining the War Hammer Titan, which enabled the creation of hardened structures and remote operation. After a timeskip, Eren’s appearance changed: he grew taller, sported shoulder-length hair, a slight beard, and wore bandages covering his forehead and left eye. He infiltrated Marley disguised as an injured Eldian soldier, wearing an armband and befriending Warrior candidate Falco Grice. His ideals solidified into a belief that absolute freedom justified extreme measures. This culminated in activating the Founding Titan's full power through Ymir Fritz, initiating the Rumbling to unleash the Wall Titans and annihilate all life beyond Paradis Island. Eren’s ultimate Founding Titan form, the Doomsday Titan, manifested as a colossal skeletal structure with an enormous ribcage and undersized limbs. Its head featured elongated hair and ears, exposed molars, and a partially fleshless jaw. The Titan moved by undulating its rib-like appendages, housing Eren’s decapitated head reconnected by spinal tissue. In his final moments, Eren confessed his actions stemmed from a compulsion to fulfill a predetermined future witnessed through the Founding Titan’s power, which merged past, present, and future. He admitted unresolved love for Mikasa and a desperate desire not to be forgotten by her, even as he accepted his death at her hands to halt the Rumbling.