The mute servant is an adventure story classic (Zorro had one), and the Count of Monte Cristo's no exception. Ali is mute because he had his tongue cut out by the Bey of Tunis, his previous employer. It seems Ali was disobeying his orders and fooling around with the harem girls he was meant to guard. He seems to have learned his lesson, however: he never disobeys his new master, the Count of Monte Cristo. He plays an instrumental, albeit small, part in Monte Cristo's much, much larger plan.