He was the godson of Al Pratt, the Golden Age Atom, and raised to becoming a hero known as Nuklon and becoming a charter member of Infinity, Inc. and subsequently served in the Justice League. He took the Atom Smasher identity shortly before the founding of the current Justice Society of America, of which he was a charter member. He viewed Pratt's son, Damage, as a brother, and acted as an older brother figure to Stargirl. While Stargirl has (or at least had) some romantic feelings for Atom Smasher, he has not yet openly reciprocated.