infinity-Man was a man named Astorr, a powerful warrior from another planet. Astorr came across Drax (Darkseid's brother), who was horribly burnt. After nursing Drax back to health, he was able to pass the role of Infinity-Man to Drax before dying of old age. It took Drax years of study before he was ready to assume the title of Infinity-Man. Drax (Infinity-Man) eventually came to serve Highfather on New Genesis, where he was acquainted with The Forever People and became a protector. Whenever Infinity-Man was needed, all the Forever People would touch the mother boxes and recite the word Taaru, thus tossing them into limbo until Infinity-Man returned the power to them.
Darkseid saw Infinity-Man as a threat and figured out a way to place him in another dimension, where Infinity-Man made a planet called Adon his home. The Forever People were able to free him from this prison.
Devilance the Pursuer had a personal vendetta against the Forever People, and especially the Infinity-Man. Devilance tracked down Infinity-Man, and the resulting battle caused the island they were fighting on to explode. The two appeared to die in the process, but Infinity-Man returned, due to the effort of the Forever People and Maya, to defeat Darkseid.
Here is the link to his bio : ( http://dc.wikia.com/wiki/Drax_%28New_Earth%29 )