He went through a rebellious phase in the past, and traces of that time sometimes resurface when his emotions run high. He attributes this past behavior to a time when he was clumsy and saw no results from their efforts, leading him to give up and take the easy way out. His past antics included addressing teachers without honorifics, hanging out with a bad crowd, bleaching his hair, and tearing up mountain passes on a Magical Wheel—behavior that Grim described as being "a textbook delinquent the likes of which you rarely see these days." He considers this a dark chapter of his life he would rather keep hidden.
The reason he turned over a new leaf and resolved to change his ways was witnessing his mother tearfully consulting his grandmother over the phone. He is devoted to his mother and used to help out with household chores, such as cooking and carrying groceries.
