Born in Hong Kong, Ryan Choi was a longtime protégé of Ray Palmer who had been corresponding with him through letters. After Palmer's disappearance, Ryan moved to Ivy Town in America to assume his mentor's place on the staff of Ivy University. Following clues left by Palmer, Ryan discovered a "bio-belt", allegedly the size and density-manipulating device used by his predecessor, and became the new Atom with Palmer's apparent blessing. Though taken with the superhero lifestyle, Ryan is a scientist first and foremost and approaches many of his adventures from the perspective of scientific discovery and investigation.