The Trill serve as hosts to another life called a Symbiont.
The Trill being humanoid in appearance and the Symbiont being a slug in appearance about 12 inches long.
Jadzia is a Trill host to a Symbiont called Dax. The Symbiont is a long life creature that lives for hundreds of years and has many hosts.
By the time Dax joins with Jadzia in 2367 there have been 7 other hosts to Dax.
It adds up to over 300 years of memories which are all passed on to Jadzia when she is joined with Dax after Curzon dies.
In 2359 her joining nearly didn't happen.
Every Trill wishing to be joined has to go through an initiate program and this involves being evaluated by a joined Trill. Jadzia was tested by Curzon Dax. Curzon found himself falling in love with Jadzia and fearing she'd discover this he recommend that she be discarded from the program.
The Symbiont commission took the Curzons advice and Jadzia was dropped.
Determined to succeed she reapplied, and feeling guilty for rejecting her she was reinstated on Curzons request.
Jadzia is joined with Dax in 2367 after Curzon dies.
Now joined Jadzias personality has changed from a shy girl to a confident women.
In 2369 Jadzia Dax joins the crew of Deep Space Nine, the new Starfleet outpost orbiting the Planet Bajor. Her role on the station is Science Officer.
Her first assignment on the station is to locate the Celestial Temple. A place in space somewhere near Bajor believed to house Bajoran Prophets or Gods. This she succeeds in and the Celestial Temple also turns out to be a stable wormhole to the Gamma Quadrant. The first known stable wormhole in history.
On DS9 Kira gets on well with everyone. She already knows Commander Sisko extremely well as Sisko and Curzon were best friends and the friendship has passed on now that Dax has changed hosts.
Jadzia Met the stations Doctor, Dr Julian Bashir on her shuttle trip to the station and he seems to be infatuated with her.
As time goes on Jadzia becomes friends with Kira and plays Tongo with the stations Ferengi crew. (Tongo is a card game of chance and strategy)
In 2372 on DS9 a conflict with the Klingon Empire looks inevitable and
Cpt Sisko (DS9's Commanding Officer) requests LT Commander Worf be temporarily assigned to DS9. His assignment there is soon made permanent and a post is created for him.
Immediately Dax is attracted to Worf.
By 2373 they are in a relationship and decide to wed.
They marry in a traditional Klingon wedding on Deep Space Nine and as Worf is a member of the House of Martok, Jadzia is welcomed into the house by its leaders.
Its now 2374 and the Federation is at War with the Gamma quadrant race called the Dominion. In response to her years of service and her recent good work Jadzia is promoted to full Commander.
Jadzia and Worf have been married for less than a year and just as DS9s crew are abandoning the station due to the war Jadzia is attacked by a Pah-Wraith pa-zessed Gul Dukat. She's just outside the Bajoran temple.
Dr Bashir is able to save the Dax symbiont but there's too much damage to Jadzia and she dies.
The Dax symbiont is now passed onto a new host called Ezri.
To see Dax's Personnel file (Short bio) CLICK HERE
Other significant events in Jadzias life
2371:
Along with Sisko and Bashir Jadzia is involved in a transporter accident that sends
them back in time to the year 2024. Thanks to the help of the Defiant crew in the
present they are returned to their rightful timeline.
2373:
Arne Darvin, a disgraced Klingon agent uses the Bajoran Orb of time to
send the Defiant back in time. Darvin wants to assassinate Captain Kirk who's
responsible for his dishonor. And if he kills Kirk he won't be able to dishonor him!
But with the Defiant crew also in the time period they stop Darvin by beaming onto Kirks ship
the USS Enterprise. They do this unnoticed by using the Defiants cloaking device.
Jadzia helps to search the Enterprise and near by space station K-7 for a bomb that
Da,rvin has planted.
Jadzia notes that she remembers this time period as one of the Dax's former host
Emony once dated Dr McCoy.