I seem to be on the pattern of character design by progressive layers on all characters simultaneously. That way they are all balanced in context of each other in symmetry. My first thought was to make this Layer about Family Definition, but I think I've already thoroughly done that. The four families here are represented by Archetypes.
Mindblade = Light/Ethics
Razorblade = Darkness/Pragmatism
Ei = Magic/Environmentalism
Rhygear = Man/Civilization
These are Philosophies that counter each other in Politics, but they also give a Color Palette to each House.
To be more clear: https://www.youtube.com/watch?v=p1LDAn7AM70
Using a Color Palette for a House means that all Characters in that Family are Monochromatic to that Color Palette, even though they may have different Shape Motifs. But, it also means that there is Consistency in Design because now all the Characters have exact Color Values and Exact Shape Motifs. Progress!
Another rule I want to install is Skin Color. Human Skin has a Limited Color Palette by variation in Melanin, and will not be connected to a given Family's Color Palette. Hair can be dyed, so Hair is included in the Family Color Palette.