I am reading a book "The Power of Film" by Suber, Howard. In that he says, "In a great many films, most of the characterization occurs in the first act, the second act is usually devoted to action, and if there is any further characterization, it often doesn’t occur until the third act. If, however, the first act is devoted to action, it is too late to begin dealing with characterization in the second or third act." In the first statement, I don't understand what he means by "if there is any further characterization, it often doesn’t occur until the third act." I was under the understanding that characterization would normally come in 1st act and early part of 2nd act, but never thought it would come in 3rd act. Does anyone know what he means by that? Any film examples? As I don't understand the first statement, second statement is also confusing to me.
Remember, he's talking about films. That's a story telling medium, but it differs from novels quite a bit. Movies follow a three act structure. YouTuber Lindsey Elis gives a fabulous breakdown of what it looks like in film. Novels don't have to do this. They don't have a run time. In fact, I think one of the biggest detriments to storytelling is feeling as though a novel has to play out like a film. A book can afford to be more episodic then a film. It can take its time to explain things. I can have tangents. I think it's far more interesting that a novel can get away with these things where a movie can't.
Random examples: Han Solo wants money, and also money, and in addition money, in the first act of Star Wars. But at the end, he turns up to help because he apparently realizes that he cares about something more than money. Sarah Connor is a scared follower through much of Terminator, but in the end she has the strength to save the day for herself and the world, if not for Kyle.
If you pay attention to what Blake Snyder, John Truby, Michael Hauge, Eric Edsen, Syd Field, Linda Seger, Cristopher Vogler and some other screenplay gurus tell, you find out that they don't much agree with the piece of text you quoted. They all have same basic principle, known as metamyth. They all have their own words to describe it, but it's still the same thing. That basic structure includes protagonist growing emotionally and socially from his/her flawed identities and weaknesses to his/her true inner self and finding the strength this true self has. This is called character arch. In the beginning the film introduces this protagonist. Then it reveals his/her flaws, weaknesses, passiveness... Then it puts this poor hero against different obstacles. And in every stage of different obstacles hero learns something. Reacting makes him better until he starts to be proactive in midpoint or near it. Then film shows us this (pro)active hero until in final struggle he/she shows us something new. Ok... There is only one introduction. But there is a lot of reveals and showing - and it is also characterization. The whole film is wrapped around characterization of protagonist. The start of character. The evolution of character. The result, the final, full grown character. Never make a mistake to think that introduction is only way to do charactarization. Never make a mistake to think it is main or most important way to do it. The Main Thing is character arch, not the starting point of it. Starting point is something you leave behind when you start. You don't carry it in your back.