Charis is an earth pony philosopher with no cutie mark who has a desire to see the world through a perspective other than her own. She keeps pestering Discord to become his student, much to Discord's annoyance. Every day she asks, and every day, he says "no."
Until one day, he changes his mind and takes on a magic-less earth pony as his protege. Now that he has relented, the draconequus is delighted with his student, realising something has been missing in his life.
Discord, now reformed, now has the Princesses watching him, waiting for him to corrupt the innocent earth pony filly.
Eventually, he does something far worse.
Edit: Featured! 6/11/14