Luna always seemed to be the princess whose struggles were seen the most out of the Royal Family. First, it was her transformation into Nightmare Moon, and then came her creation of the Tantabus. They came from her and her alone, and as such, she could only blame her own lack of self-control for how they hurt others. Eventually, with the help of her friends, she was able to defeat both and extinguish most of her anguish.

However, there was yet a third source that brought the princess pain; a last, rotting seed. It was something hidden, not only from others, but even from the mighty alicorn herself, and she needed to find and put an end to it.

...But the results of that quest were something that Luna could not so easily foresee.