The Keeper of the Warehouse is the single person chosen in each generation to protect the Warehouse's most closely guarded secrets.
The Keeper serves as a living memory for the most vital parts of the Warehouse's history, not only as a fail safe should the Warehouse fall under enemy control or become inaccessible, but also as a "backup" for files and information that have been permanently expunged from all other Warehouse records. For example, when Mrs. Frederic was searching for the reason Paracelsus was bronzed by Warehouse 9, she could find no information in any of the Warehouse records. However, the Keeper of Warehouse 13, Abigail Cho, was able to divulge that Paracelsus had been the Caretaker of Warehouse 9, and that his bronzing was not only a move to contain his dangerous artifact usage but was also an attempt to keep his knowledge of the Warehouse out of the wrong hands.
While the Keeper protects the Warehouse's secrets, the information is actually stored in the braids of Queen Ka'ahumanu’s Lei Niho Palaoa and the Keeper acts as the specific physical access point to the information. Somehow the artifact is keyed in to the specific Keeper for each generation and will only allow itself to be activated by them.