WHY IS THE CASTLE GREEN? Only time I'm going to answer: Because it's emerald. Emeralds are made in volcanic eruptions. So it makes sense that he has an emerald castle instead of say an orange castle.
So, I started making this shortly after I finished my Christmas Let it Go video. I wasn't going to continue but I had promised someone in my comments that I'd make it (Telling them exactly what I'd do). So, a few complications solved later here it is!
Credits: (Will come)