Epidemius is one of Nurgle's favorite plaguebearers.
Official Canon Edit
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 Edit
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 demon of Nurgle.