The Blood Guard was created in the year 5. Since royals were not allowed to duel in matters of honor the Blood Guard was formed as a unit to preserve and protect the honor of the Imperial family. Over time the role has become mostly a ceremonial one. Used mainly to give a place of honor and safety to Imperial heroes.
Or so the public believes. In The Burden of Duty Lord Desmond Blackstone finds that the Blood Guard is also charged with disposing of people who have the power to embarrass the Imperial family. One such target was an old friend N'rque C'st. A former ally from an earlier story Defenders of the Realm . Also the only other person left alive who knows that the current Emperor is intersex. Despite vowing to keep silent his life and career were destroyed before Blackstone was sent to finish the job. Bringing the injustice to the attention of the Emeror (at great personal risk) he saved the life of his old friend and then resigned from the Guard.
The current Blood Guard is led by Baron Knaff. A vicious and ambitious noble man who has on several occasions been an adversary of Lord Blackstone.