“Facets” is episode twenty-five of season three of Star Trek: Deep Space Nine.
Jadzia asks her closest friends on the station – basically, the senior staff plus Quark and a Dabu girl – to help her perform a Trill ritual, the Zhian’tara.
This ritual requires the use of other people’s bodies to allow a new host to meet the previous hosts that had the Dax symbiont. The memories of the former hosts are transferred to their bodies, allowing Jadzia to actually converse with them.
A Guardian is coming to the station to assist with the ritual. This is because Jadzia has been putting off performing it for some time. Partly this is because of Joran Dax, the rather unbalanced host whose existence, that had previously been suppressed, was revealed in “Equilibrium”.
The other part is the fear of meeting Curzon, the previous host, who washed Jadzia out of the symbiont programme. She is worried about meeting him, and, indeed, Curzon is more trouble than Joran. During the ritual, the various crew members act with completely different personalities.
Meanwhile, Nog is undergoing a series of tests to allow him to take the Starfleet Academy entrance exam. Quark is still not happy about this.