"The Tame Six." It's how some Ponies referred to the Mane Six behind their backs. It had nothing to do with bravery and everything to do with their attitudes toward a certain topic. During the years our heroes of Equestria were defending Equestria, other mares of their age were discovering, well other things.

After the last great battle, when evil had been vanquished and Twilight was set to assume the throne, our six sweet, pure girls began to wonder, "What was with those funny looks on the faces of other mares their age when a certain very uncomfortable topic came up?"

While there were many reasons fate chose those six Ponies, one reason had to do with a certain common trait they shared.

This particular common trait kept them from being distracted by distractions that started to distract mares about their age.
What was this trait you ask? Well, when it came to that "uncomfortable" topic, all six shared a certain coyness, shyness, prudishness, properness, as well a sense of shame and embarrassment with regard to the whole thing. You see fate knew that during those years, Equestria would need their undivided attention.

Now that those years had ended, at some point there would come a time when they would learn about the last great mystery of life.

Fate had decided that the time was now.