So I'm working on these character portraits, but I hit a wall in regards to color (mostly, anyway).
I'm not after "realism", but I can't seem to be able to add more variation, yet I feel like they should have. The two bearded guys at the bottom, for instance, maybe I should add some green on them? But using Arne's Famicube palette (because I don't think I should try and develop my own at this point) it's like there are no other options.



I'm guessing if i added more saturated colors it could work... Or it might look really weird for villains (all characters in bottom row).
Could you guys please enlighten me on this?

Thanks in advance.