Celestia, the Lightbringer.

Luna, Mistress of the Night.

Twilight Sparkle, Master of Magic.

Cadance, Princess of Love.

Of the Four Princesses, Cadance is the one that ponies think they understand the most. After all, what could be so hard about being Princess of Love?

A lot of things, actually.

The first story in the Four Princesses, Four Demons series. Sequels are Celestia the Indomitable, Twilight the Triumphant, and Luna the Faithful.

Featured from 1-26-21 to 1-29-21, all thanks to the kind folks of this site, who even pushed it to the #2 spot.