Thoughts: This is a rather straightforward image, with relatively little to relate.
Robotnik's expression was meant to be a little mixed, with one side appearing rather stern, while the facing side bears a kind of sly or manipulative look. A half-smirk hides his intent...
My primary concern was toying with the inner surfaces of Robotnik's shoulder armor and neck-lining material. Instead of the typical smooth lines of fabric, I've added various small extensions of devices; the shoulder armor has also been somewhat significantly altered as to have further functions - in this case, facial/head protection: where the inner border of the armor, in conjunction with the lower collar-tab, can slide over Julian's face and head, leaving a visor and full respiration unit. Odd, yes, but practical ... After all, having your mobility of common work time and attention is one matter, but having a helmet at hand at all times for protection is rather akward to manage. More notably, with Freedom Fighters and other irate Mobians likely out for your blood (or violent capture), it serves best to have immediate defense against attack, where bombing, noxious gas, or any other dangers where a full-body environmental containment suit is required.
Details: A short sketch and basic exercise.
Materials: mechanical pencil and Canson sketchpad paper.
Cynicide: Heh, this is what the effort of 4AM restlessness inflicts upon your eyes. Fear.