Alrighty...I don't do many critiques, so I apoligize if I sound a bit too harsh.
Snowfur's head: The ears are way too big, and the way you did the hair is overused and inaccurate. If you want to incorporate the bangs into your style, sure, but it would look better if you made it less dramatic. c: Her eyes are humongous, yet she has tiny pupils...doesn't make much sense. Now that I look at it, the head itself is very large...Here's a quick tutorial sketch up by someone I know for head sizes: [link] She recommends using a Sphinx cat for reference as you can draw the cat's structure without all of the fur getting in the way. Also, the mouth looks like it was painted on her snout. It's not connected to her head at all.
Snowfur's body: Her body looks like it is at a very awkward (and painful) angle. Her tail is much to short and fluffy for a cat and is bending oddly. I can't tell if she's sitting or standing; her legs suggest that she is standing, but I'll get to those next...
Snowfur's legs: Her legs (the back ones especially) are much too short and stubby to support her weight. Here is another tutorial from the person before: [link] The legs of a cat usually bend, but in this picture it appears that Snowfur's legs are sticks.
Bluestar's head: Like Snowfur, Bluestar's eyes, bangs, ears, and head are all much too big. However, one thing really stood out on Bluestar...her mouth. It is completely off center. I drew Bluestar's face on my own cat IRL: [link] See how odd and unrealistic it looks? Also, it makes it look rather silly, and I can see that you weren't trying to make it silly at all! This is an emotional scene from a book, after all. Here's a really good tutorial on emotion: [link]
Bluetstar's body: Bluestar's body is relatvely okay; the only major thing I can point out is that near her tail her but sticks out. Her tail is better than Snowfur's, but it is still rather short and overly fluffy.
Bluestar's legs: Bluestar's front left leg should be facing the front more, and the joint in the leg shouldn't bend as sharply. Her hind paws are unnaturally large, and her back right knee is bending too pointedly like her front legs.
The coloring in this is very messy overall and does not fit. For the shading, use a more gradual color.
Background The background is very empty, and I feel like Bluestar is too small for how far back she is. Here are some good tutorials for perspective: [link] [link] [link] [link]
I'm sorry that this is so long, and I hope I helped you to improve. c: For good measure, I'm going to link to a few more tutorials and references for you to use below.
[link] [link] [link] [link] [link] [link] [link] [link] [link] [link] [link] [link] [link]
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