Dio Promus

Dio Promus was the Chief Librarian of the Ultramarines and later a Knight-Errant serving Malcador the Sigillite. A psyker from Macragge, he voted with the Librarius at Nikaea. The edict that followed made that vote a crime.

Promus accepted Malcador’s black after the edict, entering the Sigillite’s service as a Knight-Errant. The Imperium still required psykers to act against other psykers, and the office supplied them. In that capacity he took part in the purges connected with the Titan project, hunting the psykers whom Malcador did not wish to remain alive. The war later returned him to Nikaea, where Svafnir Rackwulf, a Space Wolf, killed him.

Lemuel Gaumon took the name after Promus’s death, which allowed Malcador’s agents to continue the work of a dead man under his title. Promus did not survive his second visit to Nikaea, but the title did. The Ultramarines, his original Legion, were not consulted about its further use.