Real people seem to change. They change physically, e.g. people get older. They change roles, e.g. a woman becomes a wife and a mother, or she stays a mother but ceases to be a wife.
Change is always disturbing for us. We try to handle change in people by putting names on the change. We refer to:
* a mid-life crisis
* somebody being born again
* somebody going through a phase
* somebody being a trouble maker, or a shit disturber.
This is one of the primary reasons for fiction, to help us understand the changes in people.
There are three basic approaches to change in characters:
1. You can’t change. The characters are not transformed, they are unmasked.
2. Other things change you. For example, how you are treated by others.
3. You change yourself. This theory of change relies on the force of human will.
No matter what your theory, make sure you give reasons why your characters change.