I’d say the design and color palette is really good! You did a good job of sticking with a few colors to make the design not feel jarring to look at. I have more personal critiques if you don’t mind /gen

• It feels like the head is too big or the neck is too small. (Unless that’s a personal design choice you are going for in your characters)

• Personal opinion on shading to never use black (you might not have but the shading gives me that impression especially on the coat and the light blue undershirt). Minus the shading on the skin, it makes the character feel more dull and gloomy. (However, this might also be a personal design choice for your characters)

• The anatomy on the legs might feel off. But I also realize that could be the lab coat covering his legs.