Here's the finished sculpt along with an A-pose and 2 poses. Included some gestural sketches for the pose too. I think that I've settled for the "threat" one.
Lesson 2 - Sculpting and Posing
Rendered the images in Zbrush and also tried some environment maps in Substance!
I took a lot of liberties when translating the concept to 3D and using the Spiral brush let to tons of happy accidents that I tried to roll with. In hindsight I kinda of miss the angular shape of the shoulders.