Comment on art, first and foremost - I too remember the transition from pure black shadows to coloured darkness. It's served me well to make the shadows the same colour as whatever they're on, but darker and, most importantly, more saturated. Take the original colour, drop the brightness a bit, up the saturation. Haven't found anything better yet, at least, though I still use pure white highlights (should probably learn coloured lighting one day). The shadows on her fur are really light, too, but most of it's really nice.
...got kind of art critic-y there for a moment. I don't get to talk about the results of my art endeavours very often.
Anyhow, Catherine's certainly worthy of her own study, given how unique her figure is. It's really a shame we don't have any other female characters, at least that aren't human - it makes it really hard to have a frame of reference for dimorphism and whatnot. The combination of height, figure, and especially eyes areis kinda weird. You can handwave her really feminine figure for the most part by just saying she's one female cat out of many and it doesn't really tell us that much, but different eyes entirely is just odd. Never really knew where to go with that, honestly.