Well, if it's a story about 'the children of the sun', it could center around their origin. Maybe they are born with unique abilities because of their relation to the sun. It could also be about their journey to fulfill a certain prophecy or mission related to the sun's power. For example, they might have to use their sun - given powers to save their world from darkness or some other threat.
The 'the children of the sun story' might be about a group of beings who are considered the children of the sun. They could be a symbol of hope, light, and warmth. It could tell of their relationships with other characters in the story, how they interact with humans or other creatures. Their story might involve their growth, the challenges they face because of their special identity, and how they come to terms with their role as the children of the sun.