Even when he was young, the naturally curious Armin had a deep fascination with the world beyond the Walls. As a child, he found and studied an illegal book about the outside world that was owned by his grandfather.
 
He told Eren Yeager, his best friend, about the book and the information that was contained in it. Armin was branded a heretic by other children for his unusual interest in the outside world, and was thus frequently picked on.
 
Too timid to defend himself, Armin would often rely on his friends Eren and Mikasa Ackerman to protect him from local bullies. This, coupled with his frail physique, was a source of much shame for Armin, leading him to have poor self-esteem and to believe that he was a burden to others. Because of this, Armin has always been very eager to prove his worth. As a child, he hoped that one day he would be able to consider himself a true equal to his friends