For that piece it’s because of how it’s rendered. Quick Note: The Highlight layer is off for this one to better show off the shadows.

So, the top most layer is a true/flat color, or diffuse, layer which is the characters colors. It’s set to multiply.

Then there is a shadow tone layer; It’s a dupe of the color layer altered to change the color of the Gradient Map layer. This is to have more control of the color and get it exactly the way I want and because just on it’s own it doesn’t have enough color depth.

The Gradient Map changes the color of the shadow layer. The color of the gradient map doesn’t really matter. I need this layer to have more unique colors.

And finally is the shadow layer which is the just a gray scale layer so I can more easily color it.

Due to this set up I can easily change the color by just changing the diffuse and shadow tone (and highlight) layer.