Trogdor burned the countryside. Trogdor burned the people. Trogdor burned the resistance cells that attacked him. Taking up a lead-from-the-front position, he turned his skills as an insurgent into a devastating counter-insurgency campaign leader. Terror swept the world as graphic depictions of futile resistance promulgated world-wide with the erection of a demon-controlled communications network, announcing victories and exterminations as they occurred.
It was at this point that a very dangerous, and seeming foolish, handful of canny survivors embarked on a quiet quest. One of them, formerly an investigative reporter and historian, took to monitoring the demon media campaign along with a propaganda expert with a psychology background; the pair noticed an obvious pattern in the propaganda, centering around the way Lord Cygnus--whom they still call "Trogdor" in the survivor and the slave populations--presents himself and frames the propaganda narrative that they looked at each other and said the following:
"Overcompensating, isn't he?"
"I sense a severe 'Revenge of the Nerds' vibe here."
"I bet he was abused as a child, and this is his revenge."
"Then let's expose him. I bet his demon friends would appreciate being ruled by a runt of a punk kid."
The pair got a couple of good friends, trustworthy men, to go with them and they began an underground quest across the ruined world seeking the evidence of Trogdor's pathetic origins. Through the ruins of libraries, offices, archives, and more they scoured as quietly as they could; to cover their tracks, they passed over other helpful information--farming, herbalism, hunting, skinning, etc.--to the peoples they encountered as a way to both obscure their real objective as well as to buy their silence (if they knew more than was good for them).
It was a day or so out from the last such stop--a ruined FBI field office--that revealed the first hint of their thesis being true: a report by a now-deceased agent about a criminally anti-social boy, and the abuse and neglect that bent him that way.
"We have a candidate: Chester Lame."
"Let's trace this kid and see if he's Trogdor."