Jadzia Dax and Lenara Kahn
Both Jadzia and Lenara are joined trills - within their bodies they carry symbionts with lifespans many times that of their own. Each symbiont is passed from host to host, carrying the memories and experience of all its previous lives.
Before the Kahn symbiont was joined to Lenara, its host was Nilani Kahn. She was married to Torias Dax, the host of the symbiont which now resides in Jadzia. Nilani and Torias were very much in love, but Nilani feared constantly for her husband in his work as a shuttle pilot. Torias dismissed her worries as exaggerated, but her worst fears were realised when he was tragically killed during a test flight. Nilani had tried to persuade him that he should delay; that the shuttle was not yet ready for testing. In his heart, Torias had known that she was right, but had gone ahead with the flight.
When Jadzia and Lenara meet, they discover that the love they had shared in their previous life together is rekindled. Their meeting offers them the chance to explain to each other what had happened when Torias died, and for Jadzia to admit that the part of Torias that survives in her has always grieved that he did not listen to Nilani. They also discover that Jadzia and Lenara have much in common, quite apart from their previous relationship as Torias and Nilani.
According to the rules of Trill society, however, 'reassociation' with partners of previous hosts is forbidden, as symbiosis is intended to give the symbionts the chance to accumulate as many different life experiences as possible. The penalty for reassociation is exile from the Trill homeworld, meaning that the symbiont will die when its current host dies. The couple are thus faced with a difficult choice: either to give up their renewed relationship, or to face exile and eventually the death of their symbionts.
When an accident on the Defiant puts Lenara's life in danger, Jadzia is determined that they will not be separated again. She asks Lenara to stay with her on Deep Space Nine. Lenara, however, is uncertain that she is able to take the consequences for their symbionts. She tells Jadzia that she will return to Trill to think it over, though Jadzia believes that if she leaves, she will never come back again.
