I have in the past written about characters in a writer's creative writing efforts.
Of all things, characters should be believable. Readers should be able to relate with them.
Character Building Blocks
We all know that we should avoid detailed descriptions of our characters. Our characters come to life, when elements in their life are things the reader can identify with. Their childhood, relationships, livelihood, pastimes and outlook With these, you are able to build a person, and create a life where none existed. It is in such characters with personality that purpose resides.
A protagonist is a character who is central to the plot development in a story. You can liken this to the main star in a movie, and for a good cause. In most stories, where poetic justice is maintained, protagonists are pitted against antagonists. The protagonist is essentially the main character.
Introducing protagonists, writes Anne Allen, requires the use of strong emotions that the reader can identify with. A protagonist should, whenever possible be introduced very early in the story, preferably in the company of a few other characters to show how s/he interacts with them. There should be very few physical markers to describe characters, dialogue and deeds does a much better job.
As the story unfolds, and only after the main character and his/her story has hooked the reader, unveil more about the back-story, through dialogue and flash-backs.
Should protagonists invariably be good?
You see, there are situations where a protagonist such as Michael Scofield in Prison Break does illegal things, but the audience appreciates this and even wishes him well in light of the circumstances that have forced him to do such wrongs. This is because the audience can relate and identify with the main character's plight.
In fact, main characters will often say loathsome things and get away with it. Like every other character can, only that it'll not sensibilities as much.
Speaking of the way your characters behave, writers are faced with the tough choices of carrying within their writing, words, thoughts and actions that may be insensitive, horrendous, offensive and generally acceptable. All this however, inasmuch as both the writer and the reader may dislike such written content, is necessary to develop the plot and make the story complete. This is better explained by Gina Holmes in Tess Gerritsen's Novel Rocket blog.
So much for main characters.
What in your opinion is the best way to handle main characters. Should their deeds, thoughts and words be sanitized?