Joran Dax was a joined Trill and the sixth host of the Dax symbiont. He appeared in Star Trek: Deep Space 9. He was portrayed by Jeff Magnus McBride, Leigh J. McCloskey, and Avery Brooks (in Benjamin Sisko's body).
Born Joran Belar on stardate 1024.7, he was a renowned musician, specializing in the piano. He graduated from one of the top music academies on Trill, along with his brother Yolad. According to Symbiosis Commission records, he was a candidate for joining, but he was dropped from the program in his second year. Or so everyone believed. It turned out in 2371 that Joran had in fact been joined six months prior to that date, following Torias Dax's shuttle accident. The joining was unsuitable as Joran already had a volatile temperment, and Joran became increasingly violent and unstable. The expected rejection of the symbiont did not take place. Dax was removed from Joran, and implanted into Curzon, with a memory block protecting the host from the memories of Joran's joining, and all records of his joining were purged from Trill databases – Torias was said to have remained in a coma for the six months of Joran Dax's existence, the symbiont being removed when his isoboromine levels dropped to a dangerous point.
Joran was killed in 2285 – on stardate 8615.2 – sometime after he murdered the doctor who made the recommendation to remove him from consideration. He had killed at least two others in addition to the doctor.
The memory block began to erode in early 2371, causing severe trauma to the Dax host of that time, Jadzia. The block was removed, allowing Jadzia to reconcile the memories within herself. The information was kept secret from the general populace because it would reveal that the ability to be joined was far more widespread and possible than the Commission publicized, resulting in potential hosts struggling to acquire the 'prized' symbionts such as Dax.
During Jadzia's zhian'tara in 2371, Benjamin Sisko agreed to embody Joran's memories and personality. Aware of the dangers, the ritual took place with Sisko in a holding cell. Even so, Joran proved extremely dangerous, and attempted to attack Jadzia, taunting her about her feelings of inadequacy in holding the Dax symbiont. Unable to penetrate the holding cell force field, Joran kept in contact with it, hurting Sisko. He would trick Dax into thinking Sisko was back in control, and when she let him go, he'd attack her. Sisko regained control and Joran was eventually returned to Dax.
In 2375, Ezri Dax performed the Rite of Emergence, which brought forth Joran's memories and personality for her to interact with so she could find who was murdering the officers on DS9. Joran provided Ezri with valuable assistance in tracking down Lieutenant Chu'lak, who had committed three murders, but his constant attempts to encourage Ezri to kill the murderer in question (in addition to an innocent person who almost fit the profile) did little to endear him to his distant successor. Once the case was solved, Ezri sent Joran back into her mind, accepting she would have to be more careful then the previous hosts because he was more a part of her than of the others.