Tyrak is a Nerazim healer, specializing in treating damage to psionic appendages, as the Dark Templar commonly sever theirs.
Shortly after the Fall of Aiur he treated Lekila, a former high templar whose nerve cords had been severed by the zerg, cutting her off from the Khala. He attached energy clamps to her cord stumps for the energy bleed.
When Lekila awoke, she expressed disdain for him (as he was a Dark Templar) as well as herself, attempting to kill herself with psionic storms. He convinced her to stop, as her people cared enough for her to ask the Dark Templar for aid. He also told her that, since she was cut off from the Khala, the Void embraced her.