There's several reasons for doing study art like this:
1. It helps confirm that I understand the character before you start on the finished commission. For this piece I wanted to make sure I had the height of the characters correct and that my builds of the individuals matched what the client was imagining. In this case the client asked if I could make Selenite, the imperial officer, more flat-chested.
2. Make sure I am adapting the uniforms/costumes to the anthro pony build in a way that the client agrees to.
3. Am I getting the general personality of the characters correct. If everything checks out then move on to the finished piece. Which I will post tomorrow.