When the USS Discovery travelled to Trill in 3189, Commissioner Vos was the first to respond to their hail. Vos, Leader Pav, and Guardian Xi were eager to meet a returning symbiont and host, a rare occasion after The Burn. Upon learning the host was Human, Commissioner Vos was quick to label them "an abomination," suggesting they separate the symbiont in accordance with Trill law to protect it, killing Adira Tal.
Leader Pav refused to put the symbiont in danger by separating it, and instead ordered Tal and Michael Burnham off the planet. Vos and two Trill guards attempted to capture Tal and Burnham to take the symbiont by force, though Burnham easily stunned all three in combat.