How does a characters flaws show help and show plot development?

Answer 1

We can understand the choices a character makes and why they make them.

It helps to make the characters appear human and relatable.

The flaws can actually be part of the plot, a serial killer for example has some serious psychological flaws.

It sets the stage for confrontation, two charcaters clash for exmaple because of different or errant points of view.

Flaws are categorized as minor, major or tragic.

This link should help you further:
http://en.wikipedia.org/wiki/Character_flaw

Answer 2

The character's flaws influence their behaviors and the choices that they will make. The choices they make become part of the plot which can either build or destroy them and those they hold dear. I don't know if you've seen the Eragon movie, but here's an example. Eragon became a Dragon Rider with extraordinary powers. He received a dream in which a maiden was calling to him to save her although this was a trick of the enemy sorcerer. Despite his friends insistence, Eragon went to save the girl alone. His powers weren't strong enough and he was far too young to have proper wisdom. Because of this, his friend was killed and he and his dragon were almost killed. It was a narrow escape. Eragon's flaw was his impulsiveness and growing pride because he had become a Dragon Rider. This event influenced the rest of the Eragon's time in the story as a young Dragon Rider. The character's flaws are the cause and the plot development are the effect.