The denizens of neotoy have blue skin. Why? because of a catalytic chemical known as chlorophyll. Denizens get all their energy from the sun just like plants, all they really need to survive is water and a little bit of sunlight. I can't see why they shouldn't have blue skin, I kind of wanted them to have gray skin so that they would be more neutral but blue is better. There is of course the question of night time, clothing, lack of leaves, etc, but I think I can explain all those complications away. ie. during peak daylight hours denizens "charge" just like solar powered flashlights, then at night they have the energy to do whatever it is they do in the dark. Clothing: perhaps the type of chlorophyll in these hybrid humans reacts to wavelengths of light in either the UV (ultraviolet) or IR (infrared) spectrum. That way they could charge through clothing. Hell if I'm going to go that far out on a limb I might as well make their skin responsive to something dependable like a unique type of radiation specifically emitted for this purpose.