Nick Fury (Earth-4126)

Past
Nick's past has been erased. He believed that someone had to devote their entire life to keeping the world safe, and he thought that someone was him. He erased all connections he had, and he injected himself with Infinity Formula, which allowed him to live longer than normal humans, and maintain his youthful looks.

Alex Rogers
After Captain America's son was born, Nick kept an eye on him, occasionally helping out with raising him. After Peggy died, Nick took him in as his own. He began to train him and he gave him a variation of the Infinity Formula.

S.H.I.E.L.D.
The two of them eventually formed a spy organization known as Shield, but Nick came up with an acronym for it. Eventually, Alex left S.H.I.E.L.D. and Nick continued recruiting. It eventually got too big to remain secret, so Nick decided to go public with S.H.I.E.L.D.

Going Public
Nick had a meeting with the President and he gave Nick the right to go public, even providing him with a base out on the water called the Triskellion, as well as an additional floating guardian called the Helicarrier. The President publicly announced Nick Fury and S.H.I.E.L.D., which caused the people to appreciate what S.H.I.E.L.D. was doing for them.

Phil Coulson
When a man named Phil Coulson joined S.H.I.E.L.D., he and Nick became good friends, but also rivals. Phil was constantly working his way up in the ranks until his was Fury's right hand man. Eventually, Fury was busted for trying to form a team of supervillains in order to protect people. Phil, as well as several other agents, chased him away from S.H.I.E.L.D.

Thunderbolts
After leaving S.H.I.E.L.D, Nick decided to go through with his plan of forming the Thunderbolts, a team of antiheroes or criminals willing to do good.