It's a pretty great story, and I do wonder about the idea of expanding this even more! The artwork gives a great visualisation of the theme and backdrop around it, and I suppose some short stories or fiction of sorts could be neat. Plus, giving each character some backstory as you have done, makes the illustrations even more intriguing to enjoy.
No surprises here, the introvert gets to sit alone on Pluto, sort of like me in a way XD