This took way longer than expected, but was pretty fun! For this sort of challenge type thing, I decided to do a purple-yellow, red-green, and blue-orange character and use this to make exact complementary hues to use. If I wanted, for example, a new shade of red, I had to use the same-hued new shade of green that came with it. There were a few instances of "I really don't want the corresponding color I'll only use it for a tiny area", so if I do this sort of thing again I'm hoping to resort to that less.
The trio itself is all related in that they'd be a Pathfinder trio. The purple-yellow guy is a magus, the red-green gal is the leader and a gunslinger, and the blue-orange lady is a bard.