The Protagonist usually enters the story in Act 1 with the Character Flaw already active. This negative behavior is then challenged or changed by the interactions with the Influencing Character over Act 2 (the Adventure), and along the way the Protagonist makes incremental progress in changing their behavior. 

Act 3 begins with a Lowest Point where the Flaw returns, and then a renewed effort to overcome the Flaw in the Battle/Resolution at the end of the story. 

Changes of Character Flaw from the preceding examples:

Thor transforms from arrogant warrior to humble hero.

Carl Fredricksen lets go of his cynicism and finds hope.

Scrooge remembers that people are more important than money.

Woody accepts that the more friends you have, the merrier life is.

Transformation and change makes the Protagonist engaging and shows the audience that the Adventure is having an impact on the Protagonist. Resistance to change could result in an equally interesting tragic Protagonist. This transformation or lack of transformation helps us create dramatic conflict and thematic resonance, and can be referred to as the character arc.

There are 5 main character arcs:

NEGATIVE TO POSITIVE  - The Protagonist begins with a detrimental behavior but learns to overcome it by the end.  This is the most common type of character arc. 

e.g. Scrooge in A Christmas Carol

POSITIVE TO NEGATIVE – The Protagonist starts with a more positive behavior that descends into a pessimistic or detrimental one.

e.g. Caesar in Rise of the Planet of the Apes

NEGATIVE TO MORE NEGATIVE: the Character Flaw starts bad and grows worse.   Often this arc will end sadly or tragically, but can also be part of comedy stories.

e.g. Nina (Natalie Portman) in Black Swan.

UNCHANGED: The Protagonist’s Character Flaw does not change throughout the story, despite a need to do so. This arc is most common for anti-heroes and tragic figures.

e.g. Daniel Plainview in There Will Be Blood

IRONIC / BOTH POSITIVE AND NEGATIVE: The Protagonist makes a change that is in part positive, but it might be too late or have other negative consequences. This is the least common type of arc.  

e.g. Ennis in Brokeback Mountain, Ben (Nicolas Cage) in Leaving Las Vegas.

Choose which of these arcs would best suit your story to create the most impact for your audience.