Tunri is a member of the Maruk Ghaash'kala, formerly of the Howling Hatred Carrion Tribe. She joined the Ghaash'kala in towards the end of Olarune, 999 YK, so hasn't been with them for much longer then Bhaltair or Runmae. Much of her skin is covered with a reddish birthmark that is heat resistant, but she is not considered a Tiefling.
Hearing the call of Kalok Shash was a harrowing experience for Tunri. Her patrol had clashed with a patrol from Maruk Dar, and her group were outmatched. Nevertheless, they fought fiercely, and Tunri herself killed several of the Ghaash'kala. Her companions had all fallen, and only three orcs remained. They offered her mercy, and she spat in their faces and offered them a quick death. The dead rose around her, the flaming spirits of the Ghaash'kala closed in on her and possessed her, burning her from the inside out. In her own words, they burned the evil out of her. She was overcome with grief, she couldn't return to her tribe now, and so she wandered the Labyrinth aimlessly for a time, before she stumbled upon another Maruk patrol. She immediately surrendered, and they took her back to Maruk Dar.
She confessed her sins to Torgaan, and to her surprise, he recruited her. She now works towards forgiveness, both the forgiveness of those she hurt, but also her own forgiveness.