"Excuse me, that is incredibly offensive, could you stop-"[1]
Epidemius is one of Nurgle's favorite plaguebearers.
Official Canon[]
Epidemius' task is count the number of Nurgle's plagues and diseases that have spread, as well as coming up with new symptoms. He is an even more lazy bastard than most plaguebearers, having to be brought everywhere in a chair by nurglings.
TTS Canon[]
Epidemius is in the middle of reviewing the new disease Crotch Rot when he is assaulted with bars of soap by Leman Russ and his posse.[1]
Was present at the Battle of Khaine's Gate leading a group of Plaguebearers with the intention of getting revenge on Russ' forces. During the battle he was responsible for the destruction of most of the Deathwatch marines following Karamazov.[2]
Personality[]
Epidemius briefly displays a dedication to his work and annoyance when thrown bars of soap. He seems to take his work seriously and meticulously just like in cannon and possess a degree of distracted or disinterested calm, only responding in annoyance when soap was thrown at him: until he was swarmed in it. From this it can be inferred he finds the idea of being called clean or being clean as highly offensive which makes sense as a daemon of Nurgle.
While he is not particularly jovial, like all daemons of Nurgle he is shown to care for his fellow daemons. He refers to the Plaguebearers under his command as his "boys" and is infuriated by one of their deaths.