According to some people, Avidius is a corrupt man, forcing the citizens he is supposed to protect to give him their money. Because of this, a side quest is available to get Avidius arrested. He is also mentioned in Forged List of Candidates as having "questionable morals." 
If you attempt to accuse Audens Avidius directly while doing the 'Imperial Corruption' side quest, he will say that you attacked him. That will cause a bounty of 1000 to be placed on you, and every guard in the vicinity will also attack you. Killing him will yield a Silver Warhammer and some gold. He does not drop his armor, so defeating him does not yield great reward.
If you complete the side quest, Imperial Corruption, after several in game days have past Audens will escape the prison and attempt to kill you.