Dynamic Change in the Main Character

In my independent reading book The Last Apprentice, Thomas Wards the main character in the book changed from being a cowardice person into someone who is brave. Here is a quote in the book before he changed, "You, an apprentice to a spook! How can you do a job like that when you still can't even sleep without a candle?"(Page 8) Now here's a quote after he changed, "You see, rather than being filled with fear, i was all ice and fire, a full hot anger ready to explode."(Page 311)