Alien doctor from the highly structured and civilized Alpha Centauri Empire whose ship crash landed on Earth five years ago and has since volunteered to help G.U.A.R.D. in all things related to saving lives.
Rather than names, Alpha Centuarians are identified by their 'code'; Doctor Vega, in his native name, is known as V15-3491.
In 2009, Doctor Vega's ship, an exploration vessel interested in monitoring Earth and its inhabitants, were attacked by several vessels created by the Galactic Expatriates villain group. Their intent was to commandeer the Alpha Centauri ship and use it as their base of operations in orbit above Earth while also attempting to enslave all Terrans for the Expatriate's own demagogic means. In so doing, the Alpha Centaurians instead crashed the ship into the Rio Grande River. Nearly all of the crew died with the exception of a dozen or so. The Galactic Expatriates got away without a scratch.
As they were scavenging through the ship's wreckage trying to find weapons and high tech equipment, G.U.A.R.D.'s "Astroguardians" super-group arrived and battled the Galactic Expatriates. After driving the Galactic Expatriates away, the Astroguardians found the remaining survivors in the ship's wreckage and tried to nurse them back to health. Since no one knew how to save the varied aliens with their unique physiology, most of them died from their injuries. V15-3491 was severely injured in the crash, however, he was able to see that the G.U.A.R.D. doctors tried everything in their power to save his fellow crew mates.
After V15-3491 was strong enough, he explained to GUARD about the Empire and its peaceful intentions and practices. He told them about the various races and provided the greatest details ever on the renegade aliens that made up most of the Galactic Expatriates. He also explained that there would be no rescue mission for them, since they sent a 'ship compromised' message back to the empire, implying that no rescue attempts should be made. The message doesn't send details, however, the ship's logs were jettisoned on a trajectory back to the Alpha Centauri Empire to back up all that occurred; the problem was, it'd take 10 years to get there. In the meantime, V15-3491 mentioned to GUARD that Earth might be classified a 'hostile' planet until the proof arrived back in the Empire. To that end, V15-3491 agreed to aid the humans in whatever ways he could as a 'healer' until Earth was contacted with the Alpha Centaurians...whenever that may be.
With a life span of over 150 Earth years, V15-3491, only being 45 of those years old, was still a young alien. He has bio-genetically created powers to heal and revive near-death victims, as well as emit powerful energy auras that can strengthen a person's strength, endurance, psyche and/or memory.
Although 'logically' he should be part of GUARD's Astroguardians, the Director of GUARD decided V15-3491 needed to stay a bit closer to the Executive Division should the day come when the Alpha Centaurians arrive. Thus, they chose him to head up a new subdivision in GUARD's Medical Division: Alien Care. V15-3491's extensive knowledge of alien physiology, along with his incredible healing and aura powers, made him a perfect choice for the job; a job V15-3491 was more than happy to volunteer for.
With the code-name "Ack-Ack" (which he chose himself after seeing a certain Mars Attacks movie, thinking it was funny), the newly named "Doc Vega" has joined GUARD in their peacekeeping and humanitarian missions for Earth.