This story is a sequel to Celestia's Headlights
Celestia is bordering on her forties, her sister, her thirties. Over their lives, that ten year gap had always meant so much. It had been the difference between Celestia graduating, and Luna's first years in school. It was the difference between maturity, and Celestia's role in Luna's life as her 'big sister'.
It was nights when Luna wanted to know why she hurt, and Celestia was the only one who she trusted to explain. It was the difference between sisterly love, or sisterly rivalry, depending on how you looked at it.
Ten years.
For all it was, for all they were supposed to be together, for everything Celestia wished it could have been. Ten years only became the distance between them.