An elderly man by 2372, Bethan Roa's humanoid mind began to fail. Wanting to hide his infirmity from the Trill Symbiosis Commission, he began taking human drugs to restore his mental faculties. However, these had the side effect of dissolving the host-symbiont bond, and damaging the symbiont. Bethan Roa used this procedure to help the criminal Verad Kalon steal the symbiont from Duhan Vos, and had planned to sell the opportunity (for temporary joining to Vos) to other desperate unjoined Trill. However, Verad instead killed Bethan, and used Roa in the same way.
Pre-school teacher Ziranne Idaris became aware of Roa's situation, and had herself joined with the symbiont. She then admitted herself to Gheryzan Hospital, knowing her sister, Starfleet Lieutenant Commander Jadzia Dax, would be alerted, would question her joining, and investigate. Verad and his plot were uncovered, and Roa liberated to recover in the symbiont pools. (DS9 - The Lives of Dax short story: "Reflections")