"Kevin" was born in 2281. While disguised as a Human student aboard a ship at sea, he met a woman named Rishon. Although her parents did not approve of him, within two hours of their meeting Rishon asked "Kevin" to marry her. Kevin fell in love with Rishon, decided to put aside his powers and live as a Human. Rishon and Kevin were married in 2313, and spent most of their lives in the aquatic city New Martim Vaz, in Earth's Atlantic Ocean. He became a botanist, specializing in symbiotic plant life. He never told Rishon about his true identity.
In 2361, the couple moved to the Federation Rana IV colony, "hoping it would make [them] fall in love all over again." Their life on Rana was full and satisfying, but in 2366, the colony was attacked and destroyed by the Husnock. The moral code of the Douwd prevented Kevin from taking deadly action, even in defense of the woman he loved, so tried to fool them with his powers, though unsuccessfully. Rishon, however, attempted to defend the colonists and died along with them.
Racked with grief, Kevin annihilated the entire Husnock species (estimated at fifty billion beings). Subsequently, Kevin recreated his home and wife.
When an away team led by Commander Riker arrived to investigate the colony's destruction and the apparent survival of the Uxbridges and their home, Kevin attempted to protect his home, first with a buried snare and then by threatening the away team with a non-functioning weapon. Lieutenant Worf considered this an act of unmitigated gall, something he admired. Riker encouraged the Uxbridges to return to the USS Enterprise-D with him, but they refused.
While the away team was investigating on the surface, Counselor Troi attempted to probe the Uxbridges' minds. To hide his true identity, Kevin placed the tune from a music box of Rishon's into Troi's mind. This tune distracted her, eventually causing her considerable suffering.
Hoping to lure the Enterprise-D away from Rana, Kevin created a false warship, which appeared from the Lagrange point of Rana's farthest moon and fired on the Enterprise-D with proton-antiproton energy equivalent to forty megawatts. The crew of the Enterprise naturally assumed this vessel was the same Husnock warship that had attacked the colony, though the design was unknown to the Federation. When the Enterprise-D returned fire, the warship quickly left orbit. As the Enterprise-D attempted to catch up with it, the ship matched Enterprise-D's acceleration exactly, and the Enterprise-D was unable to catch it.
The Enterprise-D returned to the Delta Rana star system, and Captain Picard encouraged the Uxbridges to leave the planet; they again refused. After Picard had returned to the ship, Kevin brought the warship back in a slightly different configuration, and fired on the Enterprise-D with 400 gigawatts of particle energy, injuring 66 crewmembers. The Enterprise returned fire, but none of its weapons were effective, and it was forced to leave orbit. Picard hypothesized that the ship was protecting Kevin and Rishon, and to test his theory he informed Kevin that the Enterprise-D would not leave Rana IV as long as Kevin and Rishon were alive. In response, Kevin brought the warship back and had it fire upon the planet, appearing to destroy his home. Picard then ordered a single photon torpedo launched against the warship, and Kevin caused the previously impenetrable ship to be utterly destroyed so that the Enterprise would have no reason to remain in the Rana system. Three hours later the Uxbridge home, and the Uxbridges, were back. Picard had them beamed directly to the bridge of the Enterprise-D, where he explained that he had deduced that Rishon had in fact died in the attack, and Kevin had somehow recreated her and their home. Exposed, Kevin uncreated the copy of Rishon, and disappeared from the bridge. He went to the bedside of the suffering Counselor Troi and removed the music from her mind. When Picard demanded the truth of him, Kevin revealed his true nature and that, in an instant of his regretful grief, he had utterly annihilated the entire Husnock race with a single vengeful thought. Picard decided that humanity was not qualified to judge Kevin's crime, and permitted him to return to the planet and create his wife and home once more.
Colony records indicated that Kevin was 85 years old at the time of the attack, although this was of course based on his false Human identity. In reality, he had lived in the Milky Way Galaxy for many thousands of years. (TNG: "The Survivors")