In “The Sandman,” Rao is the anthropomorphic personification of Krypton’s red sun.  Despair of the Endless remarks that it would be “artful” to allow the civilization of Krypton to flourish, and then for the planet to be destroyed; and for only one inhabitant to survive - Superman.  Rao reluctantly agrees.  Sol is shown to be the anthropomorphic personification of Earth’s sun, portrayed as a toddler.

Sol is on the left.  Rao is on the right.  I’m thinking of an older brother/younger sister relationship.   

I created this image on Nightcafe.  Enjoy.  :)

Sol was in Endless Nights. The anthopomorphic personification of our sun was there to see the drama that went down with Killala of the Glow. In the Heart of a Star is literally framed as Sol telling it as a bedtime story to the very young Earth.

And like, based on what we know about the politics of whatever beings run adjacent to the Endless’ circle, the creation of the law that forbids the Endless from pursuing romance with mortals would've been very big news that’d be spread to all throughout the universe. Sol could have easily heard about it since he had a famous patron to vouch for him at the gathering in Endless Nights. Hell, because of that he might even have been at the gathering where it was first proclaimed!