Formerly known as the Imperial Blades, this storied and ancient organization is now all but forgotten in the Empire's present state of decay. Originally, they were a faction of the Akaviri army which had invaded Tamriel in ancient times, partly to hunt down and destroy dragons — their original sole calling. They eventually found their way into the service of the Dragonborn Emperors. As the bodyguards of the Septim Dynasty, they were known far and wide throughout the Empire and beyond as a type of Imperial Secret Service, responsible only to the Emperor himself.
The downfall of the Blades as a prestigious organization began with their failure to protect the last Uriel Septim at the end of the Third Era, when he was slain in the catacombs beneath the Imperial Dungeon in Cyrodiil by assassins from the Mythic Dawn, servants of the Daedric Prince Mehrunes Dagon. Even their successful protection of Septim's heretofore unknown heir Martin Septim and his subsequent self-sacrifice (which ended the Oblivion Crisis) did not save them from eventual decimation by the Thalmor nor their present obscurity.
Now reduced to two veteran members, however talented and dedicated, the Blades are desperate to regain their numbers and to defend the Tamrielic Empire — and mankind — from both the Thalmor and, now, the resurgent threat of Alduin and the Dragons.
The present-day Blades have no known allies, although apparently one survivor has been dwelling in the secretive labyrinth known as 'The Ratway', underneath the eastern city of Riften, with the abeyance of the Thieves' Guild there. They stand far apart from the only other organization known to delve into the lore of the Dragonborn — the Greybeards — and will not brook truck with them. As for the Greybeards, they will not welcome the Blades to High Hrothgar for several reasons: their violent history of genocide against Dragonkind; their known hostility towards their monastic philosophy; the fact that their high priest, the dragon Paarthurnax, dwells nearby upon the The Throat of the World and would be endangered by their presence.
The Blades formerly headquartered in the far north of Cyrodiil, at a mountaintop fortress known as Cloud Ruler Temple. This was destroyed by the Thalmor during their assault on the Empire in the Great War. The last surviving Blades, with the help of the Dragonborn, have established a suitable new headquarters at the Sky Haven Temple, which contains the legendary artefact mural Alduin's Wall.