Discord’s lack of empathy and a pony's sensibility has been tolerated by Celestia, but while both the princesses and the bearers of the Elements of Harmony struggle with even more dire problems, Discord is forced into a lesson of his own.
Twilight has discovered a new power though she is unaware of what type it is. Before she can truly being experimenting another evil begins destroying Equestria.
Barely even friends, then somebody bends, unexpectedly - just a little change, small to say the least: both a little scared, neither one prepared... beauty and the beast. [DiscoLight fluff up ahead, y'all.]