History
The original Ascendant Fleet served in the Jusadih System from 30 ABY to 36 ABY, conquering the system in the War of Ascension and becoming the new main fleet for House Plagueis. Together with their Legion, a collection of Throne-loyal soldiers and conscripts, they kept in line a system that became more and more fragmented, disloyal, and difficult to police with each year. It would see its end in the fall of Jusadih, as both the Horizon Plague and Zoraan's forces would crush and destroy the system and almost all of the ships therein. Only Ascendancy escaped.
Following Jusadih's destruction, the Plagueians found themselves stranded, but not without hope - their Trandoshan allies of Saraask'ar had called in the rest of their guild, and they had managed to come out of hyperspace at the coordinates of the derelict Vaiken Spacedock. This would be a boon to Plagueis, who used the station to start repairs on their ships. The work was slow, until freighters began to drift in, called to the Bloodsport's emergency beacon.
With help from Plagueis, and with the hard-won consent of Quaestor Reith, the reptiles of the guild captured the crews of these ships to be slaves while stealing their precious cargo. By Aedile Vorrac's orders, the slaves were subjected to Emar Xu and his twisted surgical augmentations to become a new army and crew for the Ascendancy.
Command Structure
Unlike traditional fleets and ground forces, the Ascendant Fleet has no typical military chain of command - the ships are all crewed by slaves, droids, or Plagueians when they choose. Thus, their command typically falls to either the strongest Dark Jedi aboard, the best-supported, or those decided upon by the Quaestor. Only when the Dark Jedi at the helm of any particular ship is busy will he surrender the helm, and then typically to another Dark Jedi. That said, on occasion, particularly loyal Subjugate crewmen are given the helm - though never without supervision.
In typical engagements, the Hellfire and Corsair raid fleets operate as separate entities; they carry out the petty week-to-week raids throughout various sectors in whatever area Plagueis is operating in at the time, while the Ascendant Assault Fleet only appears every couple of months and always in a different area. This strategy allows most of their strikes to resemble common piracy, even when slaves are taken; in a galaxy of trillions and even quadrillions of beings, a few thousand are never particularly noticed, especially in areas where pirate assaults happen frequently. The sudden appearance and the smash-and-grab tactics used by the Assault Fleet allow it to seem like a ghost story to most spacers and officials, as few believe the rumours of a phantom fleet of Star Destroyers emerging from nowhere to strike the unwary.
During larger engagements, the fleet comes together, with the commanding Sith of Hellfire and Corsair unifying beneath the leadership of the Quaestor of Plagueis. Then, as always, the Quaestor will fight like a pirate, ordering strikes on weak areas, strategic feints, and unfair tactics to cripple parts of a fleet and then run. Being nomadic in nature already, this makes the technical duration of a Plagueian space battle days or even weeks longer than that of a typical House or battlegroup.