Nefario was originally a biologist. He was doing research on the minions and planned to make an evil project of minions modification. Unfortunately, Dr. Mocker threatened him to scrap his big project, otherwise he would take his family's life away. Due to Nefario not succeeding in his career, the research department abandoned him.
Several years later, due to financial issues in his family, their home was sold. Everyone in his family has moved out but because they don't have enough money, Nefario decided to let his family leave him behind. Nefario, homeless, was wandering around in a park. At the same time, he met Gru and he found out that Gru was finding a Gadgetman to hire. Nefario, now a Gadgeteer, worked hard on researching and developing gadgets to become Gru's gadgetman and served him for years. He has a frenemy named Mario Mocker, who is a scientist too but he is evil and became their arch enemy.
- This is a fan-made name. Don't get confused