Vulcan from an influential family whom T'Pol married in 2154 to restore her mother's position, before he released her from the marriage.
Koss was a Vulcan from an influential family to whom T'Pol had long been betrothed. In Home, T'Pol agreed to go through with the marriage so his family's influence could restore her mother T'Les to the Vulcan Science Academy, despite Trip Tucker's feelings for her.
Koss later came aboard Enterprise during the crisis over the Syrrannites. In Kir'Shara, after T'Les's death and the fall of V'Las, Koss released T'Pol from their marriage, leaving her free to return to Enterprise and to her growing bond with Tucker.