A Cool Place to Sit

There is not much to point out, appart from the fact that his white skin could be shaded in a darker shade (so that the outlines of his muscles blend more). Fading by lowering the opacity of the lineart layer/sharpening those muscle lines with a small, sharp eraser tool would also be a good idea. It's a bit too hard to explain, so please bear with me

I can sort of tell you're using Photoshop (sorry if I'm wrong )

The shading of his dark skin is superb, same for the texturing you gave his shackles. No need to mention your anatomy skills are perfect, at least in my view.

Bonus points for the ice/colour sceme