Y'all need to give this a look.

So I keep doing plugging, but that's fine!

Legacy of the Sun By IceColt

When Celestia plans the next Summer Sun Celebration, she hopes to not only give Luna a place in the hearts of her subjects, but also to close off a complicated chapter of her past. However, just as everything seems to go fine, dark shadows start to appear and her deeds from a 1000 years ago catch up with her to put her resolve to the test ...

At the same time, The Great and Powerful Trixie, who had had only bad experiences in Ponyville, pays the location of her humiliation another visit to partake in the Summer Sun Celebration. Old antipathies soon flare up again and one unicorn especially gets her temper flaring. Yet those are the least of her problems, as she sees herself confronted with her own past and even her own heritage ...