In television, no one changes.  Sometimes characters change in serialized dramas.  Growth comes from striving for a goal, overcoming obstacles and taking action.  Yes, every episode is about a character overcoming some minor obstacle, but even if there’s a degree of growth by the end of the episode, everything typically reverts to normal by the start of the next. 

Characters all serve a purpose in telling your story.  Characters can personify a particular issue or theme: Betty Draper in Mad Men represents the oppressed housewife of the ‘60s; Peggy Olson represents rising feminism.

Characters often represent certain aspects of the point you want to make.  In Desperate Housewives, Bree is a meticulous ‘50s housewife.  Her role is to show how being perfect causes you to lose control of your marriage. 

In Sex and the City, Charlotte is the most ‘proper’ of all four women.  Her main goal is to get married.  Her role is to show how being the ideal woman, how doing what everyone expects of you still doesn’t lead to happily ever after.

Consider what you need to say in your story and how each of your characters will do that.  There is one thing about them that they believe about the world that colours everything for them.  This is how they deal with life, how they respond to everything.  This is the one thing that never changes about them.  Bree believes she has to be the perfect wife to keep a man.  Despite the fact that her marriages always fail, she never lets go of that belief.

Each character should have one point of view, but that doesn’t mean they should be two-dimensional.  Bree may have certain ideas on how the perfect housewife behaves, but compromises her values once in a while.  She also has to live in a modern world where everyone else doesn’t live by her rules: her son is gay, her first husband liked S&M.  Even though she eventually comes to accept others as they are, she still never lets go of her core belief.