"Mors Vincit Omnia" - Death Conquers All
First and foremost, the Deathsworn are the House of Bloodfyre. A black cult of personality, they are loyal to Master Sith Bloodfyre-Tarentae - the Avatar of Death. The Dark Jedi Master utilizes the cult as a sinister power base, pursuing an agenda he feels is beneficial to the well being of Clan Tarentum. It is to such an end that he is willing to confront all harmful influences - both within the Clan and without.
The Deathsworn are called such because they are sworn to serve until their death, and as adherents to the will of Sith Bloodfyre, consider themselves Death's agents in the galaxy. The Deathsworn revere death, almost as if it were a living entity, a primordial being whose consciousness actively exerts its will. Therefore, they do not fear dying, lurching forth in secret from their dark locales to curry the favor of their Master.
Functionally, they are inherently diverse, composed of individuals who express their reverence through a myriad of horrific undertakings. What distinguishes the Deathsworn from other Tarenti is their cult-like fanaticism and fervent adherence to the dark philosophies devised by Master Bloodfyre.
The Deathsworn have various origins, including the Shadesworn of Clan Arcona and the Death Dealers of Clan Tarentum. From the depths of these dark fonts crept forth the ghastly foundations of the Deathsworn.
History
Over the course of many years spent mastering the dark arts of Tarentum, Master Sith Bloodfyre and his closest disciples discovered a way by which their puissance might expand. By creating wounds that rippled through the force, the Dark Side would flourish. Those who called on it could tap into this power.
Attempting to reveal the promise of such a secret, Master Bloodfyre manipulated Anshar Kahn Tarentae into slaughtering the inhabitants of the Yridian penal colony, during the height of the Yridian Revolt. This contorted Yridia II into a powerful wound in Force, potent enough to echo throughout the entire Yridian system.
Rather than seeking to establish a personal empire, Sith Bloodfyre chose to turn this dark secret towards the strengthening of Tarentum. He refused to allow the clan to rot and decay from within, for such forces are the implements of Death himself. They would be his to wield. It was with startling wisdom that Bloodfyre recognized the ability of imminent doom to galvanize, and so he appointed an awful few to swear to his grand design.
The fanatical forces of the Deathsworn are agents of purification, striding forth into the galaxy and wreaking havok, ever strengthening the hegemony of the Dark Side - and Clan Tarentum. A secret society to the extreme, none can say for sure who are Deathsworn nor where they lurk, entrenched in the Clan of Death and acting in the name of their primordial sovereign.
Blessed are those who whisper to the Dark Side, and hear Sith Bloodfyre whisper back.
Organization
Hidden within House Mortis, the Deathsworn are without exception harbingers of the Dark Side.
Unlike the traditional combat arms units, long known as a trademark of Tarentum's military forces, the Deathsworn have little in the way of rigid hierarchy. Wicked inclinations are shared, as well as a distinct reverence for Master Bloodfyre, and each member of the Deathsworn occupies much the same place as any other: an agent of Death himself. Veneration for the Master is expressed as an element of one's personality, and none are expected to adhere to uniform criterion.
The only thing approaching an exception to this is the role of a single apprentice, chosen to lead only as an extension of Sith Bloodfyre's will. It is from the Master's authority that influence is derived, and instructions are passed to this individual for dissemination throughout the society as a whole. The being chosen for such a role occupies a place of ceremonial respect, but has little influence over the activities of any member of the cult. Sith Bloodfyre speaks, and all others act as they choose - although few elect to defy Death itself.
Etah d'Tana, Darknyte, and Thanadd Mawgath are known to have tended Master Bloodfyre's ambitions in this manner.