Every Friday, from five in the afternoon to eleven at night, Pinkie Pie does volunteer work. She doesn't have to do it, but she chooses to do it anyway. It is a matter of life and death, after all. Literally.
During one particularly stressful day, Sweetie Belle gets into Rarity's makeup. Rarity demands an explanation. The answer isn't quite as simple as one sister trying to emulate another.
From the stone age to the modern world, Celestia guides her little ponies into the future. And she needs to keep playing. Just one more turn. Always one more turn.
A mad cultist decides that the best time to fulfil a forgotten prophecy and open a portal to the interdimensional void is now. As he himself is unable to do so, he requires the aid of somepony more magical. And he knows just the pony for the job..