Grivak Tarks is a former military doctor from the Batarian Hegemony. In 2170 CE, after refusing his commanding officer's order to give him his daughter's hand in marriage, Tarks was re-assigned to torture detail on the humans captured during the raids. He was given the task of feeding and washing several of the prisoners, including Emmanuelle Sharon, a 16-year-old girl from Cailloux.
Greatly depressed by his unpleasant work, and separated from his family, he began to see Sharon as a substitute for his daughter, and showed her very small signs of favor. When his superiors found out, they changed her torture regimen, and instead of dropping random insects and reptiles into her coffin-like cell as they had been doing, they instead dropped a large and mildly venomous serpent. The spectacle of her constant pain and terror made Tarks suicidal, and unable to take any more, he helped her escape, hoping that his superiors would kill him. Instead, his actions brought the Alliance down on the base, and he was offered amnesty in exchange for defection from the Hegemony, which he took.
Tarks' amnesty only extended to a free ticket to Omega, and he spent the next ten years in an alcoholic haze, trying to forget what he'd done and the family he'd left behind, until he heard about the opening of the Robert Sawyer Center on Cailloux, a hospital devoted to treating the victims of the batarian raids. He saved up his money for months, and in 2182, he bought a one-way ticket to the colony (he convinced his human pilot that he was turning himself in for war crimes.) Upon arriving at the hospital, he begged the administrator, Pamela Nilsson, to let him work at the hospital as a form of penance for his past actions. As luck would have it, one of Nilsson's earliest patients had been Emmanuelle Sharon, who had since become a Commander in the Alliance Navy and upon learning that he was responsible for helping Sharon escape, Nilsson agreed.
Though his employment led to great controversey, Tarks has become an integral part of the life of the hospital. His sessions with Mindoir victim Talitha Paulsen, who had arrived at the hospital suffering from Stockholm Syndrome, were considered instrumental in restoring her human identity. His autobiography Four Eyes Opened, about his "journey from a torturer of humans to a healer of humans", sold millions, with all proceeds going to the hospital, and the subsequent holovid adaptation was a major box-office success. Copies of both are smuggled liberally into batarian space, where they serve as propaganda, promoting humanity's capacity for forgiveness.