Christopher Ambler became Earth's first human being born in outer space. Recognized as a "pioneer" on a new world, his parents named him after famed Earth explorer, Christopher Columbus. Chris became an instant celebrity on Earth, and businesses were quick to market his popularity. Various toys and dolls were fashioned in Christopher's likeness, and there was even a Christopher Ambler breakfast cereal.
Chris' third birthday party was celebrated at the Menlo Park station on the Earthship.
On Christopher's eight birthday, a dying alien race known as the K'L established a telepathic communique with the young boy. The aliens broadcast all knowledge of the K'L culture into Chris' mind, and he learned that the K'L represented the last 98 lifeforms of their race. They decided to take Christopher and act as his mentor. They attempted to inform Christopher's parents of their intent, but found their minds closed off to them.
Unaware of the aliens' true intentions, the citizens of Earth believed that he had been abducted by a hostile species. His father spent the next nine years attempting to track down the abductors. He eventually found them, and Earth Alliance ships attacked the K'L vessel, breaking through their force fields, ultimately destroying them. Chris Ambler projected a hologram of himself to his parents, telling them what had transpired for the past nine years. He expressed bitterness that his training had been interrupted. Declaring himself the 99th K'L, Chris elected to explore outer space in search of any surviving members of the K'L race.
Chris eventually joined the United Worlds Federation as an astronaut and pledged to explore as many alien worlds and civilizations that he could find. He piloted an interplanetary vessel named The Pioneer. Along his journey, he met the Martian adventurer, Halk, and the Venusian scientist, Jero. Halk and Jero became Chris' traveling companions and accompanied him on many of his adventures.
During the Crisis on Infinite Earths event, Chris KL-99 appeared on the partially merged final five Earths, and assisted other like-minded scientists in the construction of a massive time-travel conduit needed to send a massive assemblage of heroes backwards in time to the dawn of mankind.