Here, have a little story for this:
A fireplace is lit as two foals are chasing each other around the room, one filly and one colt. They are the only ones there as their mother and father went out with Queen Celestia and her husband for a meal.
Asteria: Lumby! You blocked the sun! How could you!? Pounces on Lumbra
Lumbra: Aste.. Why do you care? You do the same with the stars.. Sort of..
Asteria: Psht! I merely decorate the sky with my brilliant jewels of the sky! Starts to nom on his ear
Lumbra: Get off you strange filly! Mother will fix it when she returns.. I hope..