I do seem to remember you utitilizing some color before... it was an involved scene with plenty of Angels and Kats, and the color-coding helpled to keep the participants distinct... perhaps it wasn't full color, as these are. At any rate, the spectrum is rather cunningly employed here. I note that you use softer, almost pastel hues for the Angels (to indicate their ethereal natures, possibly?), while the Kats are done in stronger, more earthy tones. It really does bring the characters to life and give them definition!