Hudson was quickly invited to join Department H, a top secret research and development agency.  James was inspired when he learned of the formation of the Fantastic Four.  He intended to gather a team of his own for Canada; its first member was Logan, who later became Wolverine.  Logan helped create the team, but fell in love with Heather in the process.  Instead of causing problems with his friend's marriage, he opted to leave and accept an offer from Charles Xavier.

At first, Hudson's code-name as a costumed agent was "Weapon Alpha."  Under this name, he attempted to carry out his orders to bring back Wolverine to Department H by force.  He failed in his task, and almost killed the X-Men's ally, Moira McTaggert.  The guilt-ridden Hudson took the name "Vindicator," believing that he had to vindicate himself for his rash action.  The Canadian government finally accepted Wolverine's resignation from Alpha Flight.

Eventually Alpha Flight was created with the members Aurora, Sasquatch, Northstar, Shaman, Snowbird, and Vindicator.  The team was officially disbanded when Department H went under due to financial problems, but the members reunited to fight the mystical Beasts.  After defeating Tundra, one of the Great Beasts, the members decided to continue acting as a team performing altruistic missions.  They were joined by two trainees from Beta Flight: Marrina and Puck.  Having come to terms with his guilt over injuring McTaggert, James Hudson took the new code name Guardian.

Months later, Heather was taken prisoner by Delphine Courtney, a humanoid robot serving Jerome Jaxon, who had formed a team of his own called Omega Flight.  In the battle against them, Guardian's suit was severely damaged, and in order to defeat Box, he had to tear even more circuits out of his battlesuit.  He tried to deactivate the suit, but just as Heather entered the room, the suit exploded and everyone assumed that James MacDonald Hudson had died.

However, instead of being killed in the explosion of his suit, Guardian was teleported at faster-than-light speed through the space-time continuum, finally coming to rest on Ganymede, one of Jupiter's moons.  Unable to maintain his battlesuit's system and succumbing to the harsh atmosphere, he collapsed.

He awoke to find that an alien race, the Qwrlln, had saved him by using their advanced technology.  Unfortunately, they were unfamiliar with the human race and took the battlesuit's circuits as part of Hudson's natural body.  They created a natural synthesis between the mechanical and biological parts of Guardian.

At this point, Hudson discovered that the he had been flung thousands of years into his past.  The Qwrlln placed Hudson in a cryogenic stasis chamber so that he could sleep until he had caught up to his correct time.

When he woke up from his lengthy sleep, the Qwrlln had mysteriously vanished, leaving behind the remnant of their civilization and a spacecraft to return Hudson to Earth.

His spacecraft landed in the ocean off of British Columbia after spending two months in space.  The craft was found by a Roxxon Oil Research Rig and the comatose passenger was remanded to the company's custody.

While the organic portion of Hudson's brain slept, the mechanical section began communicating with Roxxon's Denver Facility's Computer Network through the medical monitoring device.  After two years, he was able to control and subvert Roxxon's Cyberweb. Hudson unconsciously created a series of mechanical defenses designed to protect his body.

Roxxon's Samuel Higgins, assigned to deal with this situation, called in one of their para-ops, Windshear, to help fix the problem that Hudson had become.  Eventually, Box, Diamond Lil, and Forge all became involved in the assault on this mechanical monster, all unaware that it was in truth Hudson at the center on the machine.  When they reached Hudson's unconscious body, Madison Jeffries was able to wake up Hudson's human side by interfacing with the machine part of his being and bring up images of Hudson's wife, Heather.

His reunion with his wife was a disappointment; the years spent in hibernation and his fusion with his battlesuit have drained away much of his emotion.  Upon returning to Alpha Flight, Hudson resumed using his old code name of Vindicator because his wife was known as Guardian at this point.

The Canadian government approached Vindicator, asking him to take over as leader of Alpha Flight from his wife.  The officials assumed that they could manipulate James much easier than Guardian.  James, finally understanding how these people had been controlling him, took this information to Heather and, with this revelation, the Hudsons were reunited emotionally as well as physically.

During a battle with Headlok, a creature that controlled minds, his teammates forced the mechanical portion of Vindicator's brain to take control.  When the computer part of him took over, he was able to override Headlok and defeat him.  This left him in a totally mechanical state in which he referred to himself as "this unit."  Fortunately, this was only temporary; Vindicator has since returned to his normal state.

Vindicator seems to have control over how much of his mechanical nature is visible.  At times, the area around his body shines with the glint of metal; at other times it is totally flesh.  The reason for this has yet to be explained.