A female Chiss individual was the mother of Mitth'ras'safis. Before she was rematched to the Mitth family she and her husband belonged to a very minor family. A week before their son's birth her husband lost his life saving Mitth Patriarch Mitth'oor'akiord from an assassination attempt. The Patriarch then invited the widow to Mitth family homestead on Csilla and offered to match her to the Mitth as a ranking distant, the highest family rank that could be given to a commoner. She accepted the offer. As her son had already been born, he should have likewise been a ranking distant, but the Patriarch altered the date of the rematching to happen after the assassination but before Thrass's birth, which led Thrass to be marked as a Mitth cousin to the family records.
When Thrass was visiting his mother in 37 BBY, he was unexpectedly summoned to Patriarch Thooraki's office to receive a mission to prevent the Stybla family from stealing one of the Mitth merit adoptives, a young lieutenant of the Expansionary Defense Fleet called Mitth'raw'nuru. Thrass would grow close with Thrawn over the years, eventually declaring him to be his brother. As a sign of trust, Thrass shared with Thrawn the story of how he and his mother had become part of the Mitth family.