there are many elements that make the harry potter series stand out more than any other series, one of them being character development. the characters in harry potter gradually grow and mature as the story becomes more in depth and in that way readers get more involved with the story. they begin to relate to and understand what the character is going through at that time. the characters learn to face their fears through hardships and they learn the difference between what's right and what's wrong. in that way, they find their own inner strengths, weaknesses, and a stronger sense of self which are more or less issues that we muggles encounter in our own lives.
since the beginning of the series, harry has always had a strong sense of what's right and what's wrong. that characteristic brings him the most success with overcoming obstacles earlier on (along with some help from dumbledore and his friends). his character truly starts to develop when he is faced with some of his greatest challenges such as overcoming his anger, temptation, ridicule, lack of support and, in some cases, arrogance. from the order of the pheonix on, you really start to see his weaknesses and hardships emerge. the more trials and the more adversity he faces, however, the stronger he becomes.
hermione granger is known for her academic knowledge, wisdom, and understanding of people's weaknesses. the way her character develops isn't from any new-found talents, but the way she uses the talents she already has. the first book clearly shows her as the pushy know-it-all which she constantly uses to her advantage in order to prove to everyone that she is the smartest student. however hermione learns that being the smartest isn't what's important. it is how she uses her knowledge to help her and her friends successfully defeat the dark lord and overcome all adversity.
ron is known as the best friend who always has harry's back. in the beginning, ron appears to idolize harry and believes him to be the one with all the answers (kind of in the same way as harry looks up to dumbledore). as the story goes on, ron starts to realize that harry is more or less just as human as he is, and in that realization, ron learns to rely on his own strength and courage in order for him, harry, and hermoine to defeat the dark lord.