Gristlemaw was born a Gnoll among Gnolls. Larger than most, savage, cunning, with an intuitive mind for violence and a love of conflict. Her roamed around, a raider for his tribe, until a band of mercenaries recruited him and turned him into an even more powerful killing machine; one who used weapons and armor instead of pure strength. But there was always something different about Gristlemaw. While others took pride in their prowess, or leaned on their fearsome reputations, Gristlemaw merely enjoyed the violence he undertook for it's own sake. He loved what he did, and he loved doing it well, until a battle against a superior foe left him broken and dying, with none to mourn him but the vultures that pecked at his insides.
But then the strangest twist of fate happened. A mendicant order of nuns passed by the battlefield and took pity on the Great Gnoll, and though they had little, they saved him, nursing him back to health. During his convalescence, the Mother Superior laid out the entire moral landscape in a way that Gristlemaw had never even conceived. Creatures of Good and Evil, monsters and innocents, and those who took life to protect, and those who took it for their own power.
She had a convert on the spot, and it was in those heady days of philosophy that Gristlemaw pledged himself to redemption, and to the redemption of all evil things, be it willingly, or in death.
Gristlemaw set about his task with fervor and delight, and decided that the portal was going to be a good place to start.