Ye Gods, is Charisma cute! Wow. I can look at this pic and imagine that they are actually there - as a scene, the characters and the background interact REALLY well.
You know, I think this is the best colouring job I've seen you do. Feel free to disagree, but it's another step up. I adore the colour of Charisma's fur, and the light falling on it, as well as the different shades you've used on Dark.
Blue sun: good choice. It fits nicely into the sky and gives the scene a softer feel than a starker, yellow sun would have. Of course, it could be a moon, but there's enough light in the pic (and I'm very unfamiliar with the thread) so that it's just got a certain type of lighting that works really well.