Armin Arlelt was raised by his grandfather in Shiganshina District after his parents died trying to explore the outside world via hot air balloon. His grandfather owned an illegal book showing oceans and deserts beyond the Walls, fueling Armin's intense curiosity about the outside realm. This passion made him a childhood target for bullies, relying on protection from friends Eren Jaeger and Mikasa Ackermann. Despite physical vulnerability, he resolved never to run from conflict, believing standing his ground meant he hadn't lost. He joined the 104th Cadet Corps with Eren and Mikasa but ranked outside the top ten due to poor combat skills, viewing himself as a burden. Yet his exceptional strategic intellect became vital to the Survey Corps. He devised high-risk plans relying on psychological manipulation and tactical precision, like luring the Female Titan into a trap and formulating the scheme to capture Bertholdt Hoover during the Shiganshina battle – an act that left Armin with near-fatal burns. Captain Levi chose to save Armin using Titan serum instead of reviving Commander Erwin Smith. Armin inherited the Colossal Titan by consuming Bertholdt, deepening his survivor's guilt and forcing him to reconcile with Levi's decision. This transformation granted physical confidence and a hardened perspective, acknowledging that achieving change sometimes required sacrificing humanity. He retained deep empathy, struggling emotionally after taking lives while committing to minimize casualties. Years later, Armin became the 15th Commander of the Survey Corps after Hange Zoë's death. During the Liberio raid, he directed Eldian forces assertively and confronted Eren over his treatment of Mikasa. When Eren initiated the genocidal Rumbling, Armin opposed his friend, believing mass eradication betrayed their shared dream of exploring the world. Imprisoned by Yeagerists, he escaped to join an alliance of Paradis soldiers and Marleyan warriors to stop Eren. In the final battle, an Okapi Titan devoured Armin, transporting him to the Paths dimension. There he persuaded Zeke Jaeger to relinquish his life, halting the Rumbling by severing Ymir Fritz's connection to Zeke. During a private Paths conversation with Eren, Armin mourned their fractured friendship but acknowledged Eren made him a "killer" capable of bearing their actions' moral weight. After Eren's death, Armin claimed credit for killing him to protect Mikasa, facilitating his post-war role as a peace ambassador. His relationships defined his motivations. The bond with Eren and Mikasa centered on their childhood dream of seeing the ocean – a symbol of freedom achieved only to face new conflict. Mutual respect with Annie Leonhart evolved into romantic affection; he visited her during her crystallized imprisonment, and they later fought together for peace. Senior officers like Levi and Hange valued his strategic mind, entrusting him with critical responsibilities despite his early insecurities.