That's funny. My Fallout character is also named Jack. What a coincidence.
But actually, I've always been rather fond of Joe Hockner, the 3rd Class member of SOLDIER (from FF7). Born in Kalm, raised with the desire to join SOLDIER (as many people were), and traveled to Midgar around the time Sephiroth was burning down Nidelheim (though this information was not widely circulated yet). Because of the downspin of recruitment at that time (again, this was Sephiroth's fault) the board of directors decided to put him and other inductees to the test...under the sadistic training sessions of Heidegger, whom Joe swore was trying to kill him.
At the end of his training, Joe was rated strong, but put in 3rd Class for mouthing off too much at a superior officer (i.e. Heidegger). Ironically, this actually puts him in better standing than Cloud Strife, who never actually made it in the first place. Still, because the Jenova Project was still in full-swing at the time and Hojo was injecting people right, left, and center...Joe was injected with Jenova cells and then treated with Mako energy as per the usual rules. There was...no reaction. Nar'ly a flicker, it was like Jenova wasn't even there. Further tests discovered that, in fact, it WASN'T there and the mad scientist did not know why.
But in the meantime, he had his commission, and slowly Joe became a useful member of SOLDIER. It was law enforcement, basically. He single-handedly thwarted the Notorious Chocobo-Riders Gang, whose mounts always retreated at the sign of ANY combat (easy pickins), actually went on a raid with a friend of his in the Shinra military to a raid on Don Corneo (who was involved in a black market robot buy-out and weapons deal), and eventually got involved in quelling a revolt in Sector 4 that involved a hovertank war-machine and a man with an Enemy Skill materia. (He got himself badly injured after THAT little fiasco, as did his mentor in SOLDIER.)
Later, in the furtherance of testing him and his...strangely-lacking reaction to Jenova, Joe was sent to Gongaga. Something about a monster-attack in the reactor area. He was sent alone and they wouldn't even fly him overseas. He had to take the boat and WALK. (So naturally, he spent time at Gold Saucer, just to piss them off.) Upon arriving at Gongaga, though, he found evidence that there was indeed a monster, and it was living in th reactor itself, feeding off the energy. This creature was unlike any monster ever enountered before, as it looked like it may have been human once. It was simultaneously grayish and weirdly mutated...but also rotting, and it looked like it was intelligent.
Mano-a-monstro, this was the deadliest fight of Joe's life and he was almost killed by it...until he unloaded a heavy explosive spell from his materia at the Mako reactor and RAN. Yes, I made Joe historically the reason the Gongaga reactor exploded. The actual reason was covered up, along with the creature...which was later dubbed a 'Mako-Eater' and the subject of Joe's worst nightmares from then on. The story after that involves what exactly he was doing while AVALANCHE was on the move. For instance, when SOLDIER was supposedly being mobilized, they were actually...in the wrong Sector of Midgar at the time (D'oh!).
*Pauses*
Oh dear, I do seem to be carrying on a bit. Like I said, rather fond of the tale. It was fun to write.