What change in attitude does Fix relate to Passepartout? (HELP!!)

That would be aggression, as Passepartout gives Fix a well deserved thrashing.

On that very day, however, he met Passepartout face to face on the forward deck. The latter, without a word, made a rush for him, grasped him by the throat, and, much to the amusement of a group of Americans, who immediately began to bet on him, administered to the detective a perfect volley of blows, which proved the great superiority of French over English pugilistic skill.