this website says he is the "voice behind the serpent" shrugs. He's apparently the adversary, who stands at the right hand of a man, as in a court room. He was alive and well in Job. Somewhere before Revelation is recorded he is thrown down. I think he was with Jesus. Basically AD, after Rome, after Greece and Egypt and the Mayans; he was a king of the ancient world. There is really some proof that Lucifer and Satan are the same angel. This might be Quetzalcoatl who is a birdman, aka an angel; certainly the reign of the old world dynasties. Possibly the face of the Sphinx is another contender for Satan, who is, or what he looks like, because it's so big and it's basically a king. Wouldn't that be Lucifer? Wouldn't that be the face of the king of the Old World? Are there bigger faces than that one? Lucifer was the king of the old world. Satan is an adversary who questions the goodness of Man all the time. Satan is not in Hell according to the bible and contrary to belief, he is in the vicinity of the Earth until judgment, when he will be allowed out for some time.
That's what demons are, a host of immaterial angels, part of Satan's army.
Satan fell in AD, so Satan was still running things in Rome, because Satan was with Jesus, unless we say he could materialize because God let him; or that he hadn't fallen yet.