Legion Lore
Star Boy
Thom Kallor was born on and satellite orbiting the planet Xanthu. As the 13th admitted Legionnaire, he was sometimes known as the "Unluckiest Legionnaire." He was born with the mutant ability to pull mass from the stars and imbue this mass into other people or things, thus increasing their weight and making them very heavy.
As a teenager, however, he flew his space ship accidentally through the tail of a comet, which was his first unlucky event. After recovering from that event, however, he found he had powers resembling those of Superboy. So he anxiously went to Earth, tried out for, and joined the Legion.
After a short while though, his second unlucky event happened: the Superboy-like powers faded, leaving with just the mass increasing powers. He was allowed to stay in the Legion. And then one of the few good things happened to him: he started dating fellow Legionnaire Dream Girl.
After some more, another unlucky event happened: he killed Dream Girl's ex-boyfriend in self-defense. Killing is absolutely against Legion rules, and it was shown in a Legion trial, that he could have handled the situation without killing. So he was kicked out of the Legion.
Dream Girl left the Legion because he precognitive powers weren't working properly, and together, she and Star Boy joined the Legion of Substitute Heroes for a bit to attempt to hone their powers and improve them and make them better heroes. And later still, they rejoined the Legion proper.
In later years, Star Boy was sent to the 20th Century on some mission. The trip drove him for all purposes insane. But he took up with the modern Justice Society of America as Star Man (which coincidentally had a former member named Star Man). He worked with the team for a while before it was realized who he was and he was returned to the future, and sanity.
POLT