This is the finished pencil sketch. Aside from the further fleshing out of the characters, I made a couple of significant changes from where I was originally headed. First, I got rid of the thought balloon. Once I completed the Centaur's face, his expression pretty much let's you know what he's thinking. Adding the thought balloon was redundant, and a statement of the obvious. I didn't like the blank wall where the caption was, so I shifted the door over. There was also too much blank space at the lower right of the drawing, so I added a third foreground observer. The point of all this is, I keep drawing and re-drawing until it conveys the visual balance and content that seems right to me.