Arthur is one of Elise's retainers and a self-styled "Hero of Justice". Arthur's support with Azura reveals that he grew up as a commoner in Nohr to parents who taught him that justice was acting on what his heart told him to do. More than 10 years before the events of the game he met Azura as a child when she ran away after being mistreated in the castle, and subsequently stood up for her, telling the guards that he had kidnapped her and got punished afterward, when the guards came to take her back. Since that time, he studied martial arts and decided he wanted to protect people on the streets from injustice

Voice Ref: https://www.youtube.com/watch?v=68gbPJ6023U