I know he was always intended to be authoritative (if not downright intimidating) due to his height, as well as being an eloquent, persuasive speaker. Of course, he began to lose the prettier aspects of his speech the more he turned to the dark side, using more violence to persuade others. However, in KotOR 2, there's a scene where you get a peek at how he was before his fall. Much more calm, cool, and collected. Trying to embody what he is supposed to be is difficult.