It's Grand Galloping Gala time! Discord, now fully reformed, is surprised when Princess Celestia both invites him to the party and makes a special request of him as her friend. Celestiacord. Tons of Discord!
Discord, Celestia, and Luna have lived in peace for years. But when Twilight's student-Luster Dawn -'reforms' Chrysalis, Tirek, and Cozy Glow, the chaos master and pony sisters end up involved just like the old days (as do many others). Chaos, ho!
It's been years since Celestia and Discord's first Grand Galloping Gala together after the chaos master's reform (and his confession of love). Their friendship has blossomed. But now Celestia has something to confess. How will Discord respond?