Flat and Round Characters

When E. M Forster refers to "flat" and "round" characters he says if you can express an individual in a single sentence that's a flat character.  Rounds take more description and detail.

In fiction and life, some characters seem like allegorical embodiments of vices or virtues.  Others can't be pinned down except to say they are inconsistent or unpredictable.

Flat characters:  con artist, bully, fanatic

Rounds:  no mold.  They have good and bad sides and vacillate.

Creative Write:  Develop a flat character.  Then add dimensions to round him or her.