Sisko's assignment to the station also saw him reunited with an old friend in a new form. Jadzia, a female Trill and the current host to Dax had been assigned as the science officer to Deep Space Nine. The Dax symbiont had previously been joined to Curzon Dax; a Federation Diplomat who had been an old friend and mentor to Sisko early in his career. Indeed, Sisko would call Jadzia "old man", the same nickname he had used with Curzon. Sisko, would, at times, seek Dax's advice and she would also ask his at times. Most especially when the symbiont belonging to one of Dax's previous hosts wives arrived in a new host and Dax felt conflicted. When the Dax Symbiont was passed on to a new host due to the death of Jadzia, Sisko acted as something of a mentor to the new host, Ezri Dax.