Just remembered a HIGHLY EXCELLENT sadfic based around an allegory of Twilight Sparkle being a dog and Celestia her owner, despite neither of them having any measurable influence on events at all, let alone appearing "on screen". It is likely to cause tears of sadness(said thast before, but it bore repeating) and it is relevant that it was written pre-Twilicorn.
[Here it is.](https://www.fimfiction.net/story/118727/sun-princess)
[Here it is.](https://www.fimfiction.net/story/118727/sun-princess)