I love the mystery of this story. Callisto seems rather deranged and I love the two sides of Io already. Also, I'm curious to learn of Ganymede and Europa's relationship.
I can't believe this doesn't have any comments! I really like the story idea, plus your writing is vague enough to keep me guessing while still providing plenty of details...if that makes sense Subscribed, and I can't wait for the next chapter (: