Ezri Dax

Ezri Dax was a joined female Trill, born as Ezri Tigan on the world of New Sydney in the year 2354. She served aboard the starbase Deep Space 9, the USS Defiant (NX-74205) (I) and USS Defiant (NX-74205) (II) its successor and the USS Avenitine

New Sydney
Ezri's mother, Yanas Tigan, was the owner of a very successful mining concern on the world of New Sydney. Ezri and her mother, who wanted Ezri to help run the family business, argued constantly.

Ezri refused to let her mother control her the way she did her two brothers and refused to join the family business. Instead, she enrolled in Starfleet Academy and studied to become a counselor.

Starfleet
In late 2374, Ezri held the rank of ensign and served as assistant counselor aboard the starship USS Destiny. In that year, the Destiny was diverted by a medical emergency and traveled to Deep Space 9. Upon arrival, the Destiny docked with a runabout that contained the Trill symbiont, who had been separated from its previous host, Jadzia, after she had been brutally murdered by Cardassian gul, Skrain Dukat. The Dax symbiont was escorted by DS9's chief of security, the Changeling, Odo. Dax needed to a new host in a matter of weeks or it wouldn't survive.

When a shape-shifting Founder of the Dominion impersonated Ezri's lover, Ensign Brinner Finok, and attempted to kidnap the Dax symbiont, Ezri was the first to realize that something was wrong. Soon after the foiling of the kidnapping and the capture of the Changeling, the ship was attacked by Jem'Hadar vessels. Dax's condition worsened, and needed to be joined immediately.

Ezri had never wanted to be joined, but as Brenner Finok was still missing, Ezri was the only available Trill to join Dax with. Ezri agreed to undergo the joining procedure, and became the ninth host of the Dax symbiont, Ezri Dax. Brinner Finok would later be found safe in a medical supply closet, but their relationship did not continue after Ezri's joining.