Narbithya: Shadow

A long time before most of the creatures of Narbithya existed there were two beings,  Day and Night. One day, they had a child. They called him shadow. Eventually Day and Night started to fight. When shadow took side with Night, Day cursed him. She trapped him on earth when ever she was stronger. Shadow must always hide from the light, because his mother could not bear to see him. But when night was strongest he would leave earth. That is why there are shadows during the day, but not during the night.