He was called plenty of things in his lifetime. Negan, Monster, Ringleader, John, the Comedian, etc. He was called "Dad" a long time ago when he had two wonderful boys called Dean and Sam. They were the greatest kids on Earth in his opinion and he'd do anything to protect them. Unfortunately, they were separated during the apocalypse and he was left alone in this cruel hellish world. It pained him to think about his sons, but it was better to remember them than to forget. Besides, the barbed wire bat that he kept at his side was not only a reminder of his wife who died of cancer at the start of the apocalypse, but it belonged to his eldest son Dean before the world went to hell.

Yes, he remembered it well. Sam and Dean had been separated from him by the monsters that drove humanity to the brink of extinction. Negan could only watch as his world fell apart and the things he cherished the most disappeared before his eyes. So this is what it's like to be completely and utterly helpless. He never liked the thought of being weak and helpless. He couldn't be weak in this world. It was either kill or be killed. Negan knew that his sons were still alive somewhere. How'd he know? He wasn't quite sure exactly, but he assumed that it was just parental instincts. Often he wondered if they were safe. Did they find shelter somewhere? Were they in a good group? If they could see him now, would they be afraid of what he'd become? He didn't know and he wanted to find them but he couldn't do that. It was too risky. He yearned to be with them again but he had a lot of things to take care of first (like Rick and his group). One day he'd find Sam and Dean again just like he promised them before they were separated.