Question about Season 3

In season 3, Hannibal flees to Italy to evade law enforcement. He assumes the identity of Dr. Roman Fell, but something just recently stuck out to me: What did Dr. Fell do that led to Hannibal killing him? While his motivations can range from political to petty, Hannibal has almost always remained steadfast in that his victims must be humiliated for their discourtesy. Some of his victims were homophobic or destroyed the environments of endangered animals, actions that put them on Lecter’s menu. So what did Dr. Fell do that upset Hannibal?