Born 2349, Terra. Garth was always a bit psychic, as he likes to say. He was also a technical genius and a great lover of ancient comic books. As a teenager, he read old comic books in his family's library, which they had been accumulating for centuries. His favorites were those involving the Legion of Super Heroes. Eventually, he created for himself a number of devices which gave him powers similar to some of those of the various members of the Legion. And so he called himself Legion and started operating as a super hero, just for fun. There wasn't a lot for a superhero to do, of course. Things were pretty idyllic on Earth in the mid-24th century. But he found little things.
In 2369, he was recruited by Admiral Toddman for the Psych Corps. Of course, technically Ardeen had to be in Starfleet, but Toddman managed to pull strings and get Garth into the Academy on an advanced program. Garth easily completed all his requirements within a year. It didn't leave him much time for a social life, but when it was over, he had some damn fine bragging rights. Toddman promoted him immediately to lieutenant, and assigned him to the PC. Garth needed very little of the PC's special "enhancement", as he'd already done so much to himself, himself. He was given "the Juice," as well as a few implants he didn't find out about till some time later.
Eventually, Garth developed a loyalty to Shadow Star, more than to Toddman. Most of the PC did, but Toddman had taken countermeasures against this. He had installed control devices in most of their brains, as well as puting people in the PC who he knew would be loyal to him and the Conglomerate. Later he even put in clones and a few changelings, during the brief Dominion-Conglom alliance.
Ardeen, over the years, became one of the PC's top operatives, and continued to advance through the ranks. After the Conglomerate War, when "the boss" Shadow Star dropped out of sight, Starfleet Special Ops (or Spops, as some in the PC took to calling them) promoted Ardeen to captain and gave him the task of puting the PC back together, and determining which agents were loyal to the Federation, and which were Conglom agents who still hadn't been found out. It was to be a long hard task which Garth didn't much care for...
In 23... *sigh* '77 or '78, i forget... he retired from Starfleet to become Chief of Staff for the new Vooworshii Alliance's starfleet.
But upon graduation, a few of his friends were recruited for the PC, and he managed somehow to tag along with them, despite the fact that he wasn't a member and it was all supposed to be top secret stuff. None of his friends ever questioned why he was allowed to hang around PC Headquarters or even occasionally go on missions, because it just never occured to them to wonder about it. He was the sort of person who was just always around, whether he was supposed to be or not. They had gotten used to it through all the years at the academy, and some of them had known him even before that...so it just seemed natural.
Occasionally he was nowhere to be found, but no one really noticed. They barely noticed when he was there, and didn't ever think to look for him when he wasn't. Everyone liked him well enough, but his presence or non-presence always seemed sort of an unimportant side-issue to everyone, except the closest of his friends. And sometimes even they failed to notice him. But Nick made sure he was well known by everyone in the PC, especially anyone who seemed particularly important, like ShadowStar or Legion.
Nick is currently a lieutenant commander, but most people you ask in the PC probably wouldn't know that for a certainty, not paying much attention to him. Even Nick would probably have to think for a minute before remembering himself. He'll answer to anything, including plain "lieutenant," though most people just call him Nick.
...It eventually turned out (in the Original Rounder Trilogy continuity) that he had been led to believe he was the bastard son of Luthadias Jerrickson, and half-brother to Matt and Chris Jerrickson. This was actually a ploy on the part of Admiral Toddman, who wanted a mole within the PC, to make sure his own people wouldn't plot against him, or at least that he'd be forewarned if they did. Nick was given false memories of his mother having told him who his father was; he'd never known his real father, anyway. So Nick became a member of the Conglomerate, before their existence became generally known. Luthadias went along with Toddman's deception, and they and Admiral Necheyev were the only three people who knew about it- in fact, few other members of the Conglomerate even knew he was a member.
However, this trick backfired, as it led to Nick feeling a certain loyalty to those he believed to be his family- Matt, Chris, and most especially Luthadias. This was the reason he originally hung around with Matt and Chris, before he was ever approached by Toddman to work as his spy. However, he never told anyone, including his "brothers" that he was related to them. When Toddman did make him an offer, he had no interest in refusing it. So, Toddman and his co-conspirators arranged for him to be permitted to hang around with the PC generally, and also managed to subtly influence the minds of others in the PC not to wonder about his free access.
The backfire came when Matt was corrupted by Palpatine, and later killed Luthadias. Nick was willing to do a great many illegal, even immoral things- but he did have his limits. He knew his supposed brothers quite well, and knew they'd never have anything to do with the Empire or the Conglomerate. Certainly he didn't like people tampering with his own family's minds- perhaps ironic, considering he only believed them to be family because his own mind had been tampered with. ...Still, he believed the true Matthew Jerrickson was now as dead as his father, and whatever was inhabiting the shell that had once contained his brother was responsible for his father's death. Because his years with free access to the Conglomerate, PC, as well as regular Starfleet, he was in a position to know a great deal about a great many things, and never told anyone everything he knew. One thing he knew was that there was a faction of the Conglomerate that supported Luthadias more strongly than the Empire, either under Palpatine or Matthew Jerrickson. And so he joined them. Many were rooted out by Jerrickson and his people, and killed or reeducated, but others remained hidden, and worked against the Empire, even sometimes working with the Federation. Nick became an unofficial liason between the anti-Empire Conglomerate faction and Starfleet's Intelligence operatives working inside the Empire.