Solun Decius

Solun Decius was a Barbarus Death Guard of Nathaniel Garro’s Seventy who became the daemon known as the Lord of the Flies on Luna. He served among the loyalist company that Garro drew from the XIV Legion in the aftermath of the Isstvan III atrocity, when Horus turned his guns on his own Legiones Astartes and the Seventy became fugitives rather than traitors. Aboard the escaping vessel Eisenstein, First Captain Grulgor infected the company with the affliction later named Nurgle’s Rot, and Decius carried the sickness through the warp passage to Luna rather than shaking it off as a soldier’s wound. The transit completed what Grulgor began: by the time the ship reached the Sol System, Decius no longer returned to duty as a battle-brother but as something the warp had remade in the Death Guard’s new and unchosen image.

That remaking surfaced at the Somnus Citadel on Luna, where Garro and his fellow Knights-Errant confronted the thing Decius had become. Flies attended it and would not leave it, and the encounter ended with Garro killing him, one Seventy loyalist set against another in a chamber meant for the Emperor’s own agents rather than for daemon-hunting. The killing was not, however, an ending. Whatever inhabited Decius under that title did not depart with his body, and the same Lord of the Flies presence is recorded as later occupying the bodies of Meric Voyen and Varren, two more of Garro’s circle, so that the name Decius travelled from host to host independently of the man who first bore it.

The episode marks one of the earliest instances within Garro’s company of a principle that would recur across the Death Guard’s long transformation into Nurgle’s Plague Marines: that infection by the Rot was not a wound to be treated but a claim staked by something that outlived its first victim. Decius, or the entity that used his name, stands among the Seventy less as a fallen individual than as a demonstration to Garro and his surviving brothers that Barbarus’s sons could be lost twice over, first to the Warmaster’s betrayal and then to the daemon that followed them into the Sol System. His present status remains that of a daemon bound to the title Lord of the Flies rather than to any single body, a distinction that Luna rendered academic and that later hosts only confirmed.