Centuries ago, a small group of Tremere, fearful that the Sabbat would destroy the Camarilla and their Clan in the process, defected to the smaller Sect. They offered their skills as thaumaturgists to the Sword of Caine, in exchange for safety from their former Clan. The Sabbat, not able to turn down the benefits of blood magic (despite how much the Tzimisce objected), took them in.
Reaction from Clan Tremere was swift, of course. The Warlocks conjured a curse that branded every Tremere antitribu with a mark, one that only “true” Tremere could see. Unable to hide what they were, the Tremere antitribu stayed in chantries, providing support and knowledge to their comrades.
This state of affairs continued for centuries. The Tremere antitribu contributed much to the Sabbat. They worked with the Tzimisce to create the Blood Brothers, they prevented the Camarilla Tremere from destroying the Sect from afar, and, of course, they tutored other Sabbat Cainites in blood magic. And then one horrible night, they all died, burning to death in a mysterious conflagration that afflicted each and every Tremere subject to the traitor’s mark. Interestingly, those few Sabbat Tremere who had defected from the Sabbat to the Camarilla were not destroyed, which might shed some light on the massacre’s origins.
Weakness: The Tremere antitribu were all immediately recognizable as traitors to Camarilla Warlocks. The mark wasn’t a physical disfigurement, but a change to the character’s very presence. This wasn’t a weakness that carries an immediate mechanical disadvantage, but once identified, the Tremere antitribu could expect to be hunted down and burned as soon as the Tremere can possibly manage it. They were also still susceptible to the power of the blood, gaining a +1 to all Vinculum rolls.
In addition, Tremere antitribu were barred from taking leadership roles in the Sabbat.
Quote: It’s always been inevitable. That’s why we joined up in the first place.