The Count of Monte Cristo
How we cite our quotes:
Danglars nodded to show he was satisfied. In the eyes of the world, and even in those of his servants, Danglars played the indulgent father and good-natured fellow; this was one side of the part he had chosen for himself in the popular comedy he was playing: an appearance he had taken on, which seemed to suit him as it suited the right profile of one of those masks worn by the fathers of the theatre in Antiquity to have the lips turned upwards and smiling, while on the left side the lips were turned down and sorrowful. We might add that, in his family circle, the smiling, up-turned lips dropped and become down-turned and dismal ones, so that most of the time the good-natured fellow vanished, giving way to a brutal husband and tyrannical father. (95.9)
Here's a more common kind of transformation. In the same way as you might have an indoor voice and an outdoor voice, Danglars essentially has an indoor personality and an outdoor personality.