This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
When the USS Discovery traveled to Trill in 3189, Commissioner Vos, Leader Pav and Xi (representing the spiritual community) were eager to meet a returning symbiont and host, a rare occasion after The Burn. While Commissioner Vos was quick to label the Human host, Adira Tal, "an abomination," Xi suggested learning more given how few Trill left were capable of joining.
Though Leader Pav ordered Tal and Michael Burnham off the planet, Xi found Tal and Burnham escaping capture and showed them the way to the Caves of Mak'ala. There, he prepared Tal and later Burnham for communion with the Tal symbiont in the symbiont pools. Once Tal's memories were restored, proving the viability of non-Trill hosts, Leader Pav commended Xi for the great service he had done, impacting generations of Trill to come. (DIS: "Forget Me Not")