Character Development.

Main Character resolve. 
This is the idea that the character either changes or it doesn't.
Take harry Potter. The character Harry doesn't change throughout the movie. Once he knows his special power he immediately sets out to find out who he is and how to get rid of Voldermort. His character is very determined and his mind is set. He wont change.

Main Character Approach. 
The character is either a be-er or a do-er. A do-er is somebody who addresses the situation physically, they try to accomplish their task by doing things. A be-er is somebody who prefers to work the situation out internally- they think about it.
It is possible to be both a do-er and a be-er, either approach will work to solve a problem.
Harry Potter is very much a do-er. He knows what he wants and he is very determined to succeed. Ron Weasley however is both. Where he would prefer to not be involved but when it actually comes to it, he is willing to do what is necessary.

Main Character Mental Sex. 
This is about ways of solving problems- much like a do-er or a be-er. There are two types of mental sex- Male or female.
Take a date- Male mental sex's would see the flowers, the money spent, the good food and the time you spend together all adding up to the moment you kiss. People with female mental sex's would see the combination of music, the atmosphere, the other persons behaviour and conversations you have.
Neither point of view is right or wrong, but one carries more weight for the character and affects how they perceive and decide things.

All these points helps add a sense of being to your character. It makes the character more believable when you know how they think, and the way they do things.