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Hissrad is the "real name" (to the extent such a concept can apply to the qunari) of the qunari mercenary captain and Ben-Hassrath agent Iron Bull. Depending on player's choice he can turn against the Inquisitor.
Like other qunari loyal to his native homeland, Hissrad's name is actually the title of his job, meaning "Keeper of Illusions", or more bluntly "Liar" in his native language (a fact he is somewhat embarrassed about) He was raised and trained by Ben-Hassrath fighting, espionage and masking emotions. He spent most of his life fighting Tevinter, Tal-Vashoth, Fog Warriors, spies and traitors. On day Ben-Hassrath assigned him to Orlais, there he acted Tal-Vashoth and captain of Bull's Chargers mercenary company. Bull used his mercenaries to gather information on Orlesian nobles and delivered them to the Ben-Hassrath.
The Inquisitor can recruit him to fight Corypheus. During the course of the main game, he remains perfectly loyal to the Inquisitor and forthright about his real job as a spy for his people. In one quest, however, the Inquisitor is backed into a strategic corner that forces Hissrad to chose between allowing the Chargers to die or a ship full of other Qunari. Should the Inquisitor pressure him into saving the Chargers, Hissrad abandons the Qun and embraces his identity as the Iron Bull, fully joining the Inquisition. Should the quest be never attempted or the Chargers abandoned, Hissrad becomes utterly loyal to the Qun, and during the Tresspaser DLC is eventually ordered by Viddasala to turn on the Inquisitor, which he does without question.