Castilla the Moon is... Well...... A...Moon. Thing is, Castilla is always a lumoscent blue, which makes her different than other Moons. I think you're thinking; WHAT? A MOON? Thing is, Castilla was'nt always a Moon. Let's time travel; 3756 years ago, a wizard turned a young human girl into a Moon. The reason why is because the wizard had a hatred for humans, and thought Castilla was dangerous. Thing is, Castilla was'nt dangerous... Um, and the spell lasts for eternity, so Castilla is stuck as a Moon. She leads others where they are going safely with her soft blue light.