Eclipse is the combination of two sides, To put it simply- good and bad. Like a Ying-Yang (Or like Yin-Yang from Inanimate Insanity), they balance each other out, but continue to have quite the temper towards each other. Moon, the kind one, is more timid, and smaller than Sun, like how the sun is going on top of the moon during an eclipse. They are constantly bickering, but they know that they couldn't live without each other. Each of them only controls one arm and leg.