Would this Roman Emperor happened to have been stabbed to death by all his senators and his best bud?

No, Julius wasn't mad, but he set the scene, by taking Rome from a democracy to an Empire. It was the totally mad Caligula I was thinking of, although Daros is not as dangerously mad as Caligula (who did some very vile things). Daros is paranoid rather than schizophrenic; a state of mind which is encouraged by his previously mentioned cousin, Karios, the Jackal.