A Trill man in the episode Equilibrium, brother of the composer Joran Belar, whose account of Joran's last months reveals to Sisko and Bashir that Joran had been joined.
Yolad Belar is a Trill civilian contacted by Benjamin Sisko and Julian Bashir in the third-season episode Equilibrium. The two are trying to explain why Jadzia Dax is haunted by a piece of music and by the image of a masked killer, and the trail leads to a dead composer named Joran Belar.
Official records say Joran was an initiate dropped from the joining programme who killed a doctor and died soon afterwards. Yolad tells a different story: his brother was a gifted but violent man, and for the last six months of his life he claimed to have been joined, and his character changed.
That testimony contradicts the Symbiosis Commission and lets Sisko and Bashir work out that the Dax symbiont had been placed in Joran, an unsuitable host, and that the memory was suppressed to protect a secret about how many Trill can be joined.