Every pony in Equestria knows Princes Twilight had rule Equestria far more than a thousand of years.
Always talk with soft voice; Princes Twilight is the most powerful Alicorn record in the history. She controls the changes of day and night and six different elements of harmony. With those elements she had saved Equestria from crisis, many many times.
But no pony knows why Princes always seem sad. No pony knows why she never smiles.
One day, without any warning, Princes Twilight was down with a serious illness.
AN: It is a story some may not like… because it contains "death" element, and maybe kind of heavy. Happy ending promised. (If that count.)