One of the first recruits to join the Renegade Soul Drinkers Chapter after the first Chapter War which had torn the Soul Drinkers into feuding factions, Eumenes was dedicated to the idea of the destruction of the Imperium. After his initiation as a full Battle-Brother, Eumenes challenged Sarpedon to ritual combat to make this the Soul Drinkers mission, but failed and was imprisoned while the rest of the Chapter followed Sarpedon.
While the majority of the Chapter was engaged in a campaign versus Orks, brothers loyal to Eumenes freed him and seized control of the Soul Drinkers' Space Hulk, using its resources to target loyal Soul Drinkers engaged planetside. In order to save as many of his brothers as he could, Sarpedon vowed to follow Eumenes if he agreed to rescue them. Eumenes agreed, sending shuttles to ferry all Soul Drinkers off the planet and in the end, saving Sarpedon from a Howling Griffons Librarian.
Eumenes then had Sarpedon imprisoned and had assembled the Chapter to declare that they would now wage war against the Imperium when news reached him Sarpedon had broke free. Even as he was ordering a search for him, Sarpedon ambushed Eumenes and killed him, declaring he had no honor and did not deserve to be Chapter Master. Sarpedon reclaimed the title of Chapter Master and held a funeral for Eumenes as a full battle brother.
- Soul Drinker Omnibus (Novel) by Ben Counter