Eren Jaeger resides in Shiganshina District, son of the local doctor. He burns with a fierce desire to explore the world beyond the confining Walls, viewing life trapped within them as little better than livestock awaiting slaughter. This conviction fuels his resentment toward those who accept their restricted existence. Physically, Eren possesses a rounded face, expressive green eyes, and short dark brown hair styled with middle-parted bangs, often appearing with a somewhat tan complexion. His typical attire is a green shirt and brown jacket.

His deep friendship with Armin Arlert is anchored in their shared dream of escaping the Walls. Together, they pour immense effort into constructing an airplane, believing it their sole means to breach the barriers and reach the outside world. Eren also forges a close bond with Mikasa Ackerman when his father begins regular visits to treat her ailing mother. During these visits, he urges Mikasa to explore the nearby woods, challenging her fears by comparing a life of avoidance to "chickens in a coop." Calmly, he later reports encountering wolves feeding on human remains alongside her.

Eren faces hostility for his beliefs. After defending the Survey Corps against insults in Shiganshina, he is severely beaten by two men. This violence prompts his father to consider relocating the family to the mountains, expressing concern over a "dangerous driving force" within Eren that could lead him to harm. Later, Eren gifts Mikasa a caged butterfly, explaining Armin crafted it, and reveals the completed airplane. He confides his imminent escape plan to Mikasa, instructing her to safeguard his scarf and promising to return for her once established outside.

The escape ends tragically as the airplane crashes into the Wall during takeoff, resulting in Eren’s death. This occurs before the fall of Wall Maria or the Titan incursions of the main series. His father’s earlier fears about his volatile nature and the peril of his ambitions are realized in this outcome.