Goran'agar was a Jem'Hadar in service of the Dominion. Unbeknownst to him, Goran'agar had a genetic mutation, which occured during his conception, which allowed him to survive without the use of ketracel-white.
By 2369, Goran'agar had become a First, and his ship crashed on Bopak III, but he alone survived. Only having enough white supply for six days, Goran'Agar was able to extend it to eight days, before it ran out. Expecting to die a slow and painful death, Goran'agar was surprised to find he no longer needed the white, believing that the local plantlife or water supply he had sustained himself on had somehow cured him. After thirty-five days on the planet, he was rescued.
In 2372, Goran'agar, wanting his men to be free and lead a peaceful existence far away from the Dominion, inspired five of his closest squad members, including Arak'Taral, Temo'Zuma and Meso'Clan, to steal a ship and escape the Dominion to Bopak III, where he directed them to eat and drink from the same sources he had in the hopes of curing them.
Goran'agar became increasingly frustrated when these efforts failed, and was also concerned when the meager supply of white he had brought with him began to run out (lying to his squad; saying he had enough for several months). However, he saw his chance to save his squad when Chief Miles O'Brien and Doctor Julian Bashir, investigating a magneton pulse from Bopak's surface (really coming from Goran'agar's ship's warp core), crashed their runabout on Bopak's surface, where Goran'agar and his troops promptly captured them both.
Upon learning that Bashir was a Doctor, Goran'agar told him of his freedom from the white and ordered him to begin looking for a cure for his men. Bashir, in the end, discovered the truth behind his immunity, and when his men learned of this, Goran'Agar's troops rebelled against him and attempted to kill Bashir and O'Brien. Goran'agar helped Bashir and O'Brien escape, but remained on Bopak, as he was insistant he had to hunt down his men and give them a quick death, rather than let his "brothers" die alone and in pain. (DS9 episode: "Hippocratic Oath"; CCG: The Dominion)
O'Brien and Bashir both agreed to keep their efforts on Bopak a secret, but O'Brien later confided his secret to Worf several weeks later, and Section 31 Agent Luther Sloan mentioned Bashir's efforts to help Goran'agar during his "interrogation" (really a test into Bashir's loyalty when considering recruiting him into the organization). (DS9 - Prophecy and Change short story: "Broken Oaths"; DS9 episode: "Inquisition")
Goran'Agar, after mercy-killing his own men, attempted to escape pursuing Dominion forces, but was captured. Instead of being killed for his insubordination and desertion, Goran'agar was instead reduced to Second and assigned him to serve under First Talak'talan during the Dominion War, which was discovered by Klingon Imperial Intelligence. (DS9 video game: Dominion Wars)
Shortly after returning to the Gamma Quadrant, Odo, who wished to send a Jem'Hadar emissary to establish peaceful relations with the Federation, searched the Dominion's legions for a Jem'Hadar with the same mutation Goran'agar had to negate the need for white for the emissary. Four such mutants were found and one, an Honored Elder named Taran'atar, was sent to Deep Space 9. (DS9 - Avatar novel: Book Two)