NEEK (And I worked this out ahead of time with Tar)
Nick Fury's daughter Daisy was a military pilot when K-DAY happened, and she died taking down the Trespasser Kaiju, the first of his kind. Once the PPDC was formed, he joined up and began training to be a Jaeger pilot. He found out he was drift compatible with fellow recruit Jessica Drew, and the pair would graduate from the academy and go on to pilot a Jaeger together, the Arachnid Fury (a mark one equipped with several large guns and electric blasts to stun and venom blasts with a corrosive meant to eat away at a Kaiju's skin). They drifted together for five years until, in 2021, a catastrophe ended both of their piloting careers.
During a battle, Jessica blacked out and Nick was forced to finish the battle on his own- one of the few pilots to ever use Cerebro alone and survive. This battle ends with the Kaiju killed and the rescue of the boy who will become Nick's adopted son, Alex Aaron. After they are forced to retire from active duty, piloting alone, Jessica tells him that in spite of all the precautions pilots take, she got cancer from exposure to the nuclear powered Jaeger. Fury learns that he, too, has been affected after piloting alone and that, if he were to pilot a Jaeger again, the strain on his mind would likely kill him. Despite this, Nick has piloted a few times since with Coulson ((if Devon is good with that)) but has found his health deteriorate considerably every time he does.
After his retirement from piloting, Nick is promoted to Marshall of the PPDC and he becomes a teacher at the Jaeger Academy, training new pilots. Later on, Fury finds himself at the LA Shatterdome where Jessica is also a trainer. He has taken command of LOCCENT Mission Control and continues his teaching duties. He is beginning to grow worried as the attacks become worse, more pilots are lost, and the scientists predict catastrophe on the horizon.