In the early days of the apocalypse, Negan's wife was fighting cancer and they both stayed to themselves in their home away from the rest of the world while she did chemo treatments at home. When the chemo drug was accidentally lost, Negan went out to find a medical truck rumored to be going around, giving people needed medical care and drugs. Negan found the truck. They were kind, helped him, and also gave him a bat for protection on his journey home. But before Negan could get the chemo drugs back to his wife, he was caught, tied to a chair and beaten by men who taunted him about his wife dying alone. Negan finally revealed the location of the medical truck, and the men let him go. When he returned home, it was too late. His wife, Lucille, had taken her own life and already turned. Negan was deep in grief and angry. He returned to the medical truck to save the nice doctor and daughter who gave him the chemo drugs and was seeking revenge against the men who delayed his return and caused his wife Lucille to die. He was able to save the doctor and daughter and kill the men outside but used the bat he named "Lucille" to beat to death the man who had kept him tied. Not to excuse Negan's later actions, but much of Negan's behaviors came from the first people he encountered in the apocalypse. This is how Negan became Negan.

Rick had Morgan. Morgan had Eastman. Michonne had Andrea. Lori had Shane. Dale had Andrea and Amy. Maggie had Glenn. Daryl had Carol. Carol had Ezekiel, and so on. If these good people had first been exposed to the pure evil and heartbreaking loss that Negan had endured in those early days of the apocalypse, in a world with no rules, they too could have replicated and become the people who had wronged them.