He is the destroyer. Drinker of demon blood, first slave of Mannoroth, he who ushered in the Blood Curse and the bloody haze of rage and battle frenzy it woke in the orcish heart. He was in the vanguard of the army that stormed Shattrath, the last and greatest of the draenei cities, and no axe can be said to have slaughtered more of them. No hand was more stained, not Gorefiend, not Deadeye, not Bladefist. In a sea of names that denote battle hardened warriors, his name stands out.
He is the savior. He is the last survivor leading his people when most of their kind were imprisoned and defeated. He was the one who showed the young Thrall a free orc, taught him their language and pointed him to those who would show him his ultimate destiny. Tripped up by his fury and guilt, twice he stumbled back toward the blood haze that dominated his people, the curse he himself brought upon them. Finally, goaded beyond endurance, it is the same bellicose anger that has granted him his greatest successes and his greatest failure that frees his people.
Grom Hellscream drank the demon Mannoroth's blood and led his people into slavery. Grom Hellscream slew the demon Mannoroth and led his people out of slavery. Few beings can be said to be the best and worst of their people at once -- but then again, few people can say they are the Giant's Heart.
Who was Grommash Hellscream?