Keeper

The Keeper of the Warehouse is the single pony chosen in every generation to protect the Stable's most closely guarded secrets.

The Keeper serves as the living memory for the most vital parts of the Stable's history and as a fail safe for files that have been permanently expunged from all other Stable records.

If the Stable would ever fall under enemy control then its' closest secrets would kept safe in the Keeper's hooves.

Twilight Sparkle is Keeper of Stable 13