Marley is the perfect picture of devotion; however, Marley's boisterous temperament often hides his fierce love for the Grogan's. Even John is skeptical that Marley would rise to the occasion and choose to protect the family over trying to get an intruder to play. Marley's loyalty is nonchalant. He does not make a grand show of his feelings for the Grogan's, but he is there when they need him the most. Marley has an internal sensor that alerts him to the emotions of his owners enabling him to turn down his excitement while providing a head to cry on, a comforting companion, a punching bag or a watchman. As soon as the crisis passes, Marley returns to his happy-go-lucky self.