Lieutenant T'Ryssa "Trys" Chen was a female born in 2354 to Human mother Antigone Chen, and Vulcan father Sylix.
When she was about two years old, her parents divorced, and her mother retained custody. She never knew her father while growing up, and self-identified more as a human than a Vulcan. Feeling that her mother, a Starfleet officer, resented her presence, T'Ryssa ran away from home several times over her childhood, the first time at age seven, after learning of the kahs-wan ritual in Vulcan culture. At that time, she was taken aboard a Barolian freighter as ship's cook. After a week, a Starfleet security contingent tracked her down and reunited her with her mother. She also often escaped from her mother by hiding within the Jeffries tubes of the ships on which her mother was stationed.
In 2364, at age ten, Trys and her mother were stationed at the Starfleet research station on planet Maravel. This location was the favorite of her mother's many postings throughout Chen's childhood.
Sometime before 2369, Trys and Antigone were posted aboard the USS Odyssey. They were amongst the non-vital personnel off-loaded at station Deep Space 9 when the Odyssey traveled to the Gamma Quadrant to confront the Jem'Hadar.
T'Ryssa Chen entered Starfleet Academy at age seventeen. It took her five years to graduate, finally earning her commission in 2376, after the end of the Dominion War. She served on several ships, usually transferring after a brief period, making few friends other than short-term lovers. By mid 2380, Chen was serving aboard the USS Rhea. That year, while surveying planet NGC 6281, the Rhea was attacked by a Borg ship. However, an encounter between Chen and an entity living in NGC 6281 halted the attack, and inexplicably transported Chen to the planet Maravel.
She was then transferred to the USS Enterprise-E as contact specialist when it went to NGC 6281 to investigate the Rhea's fate, and to keep the Borg from potentially acquiring quantum slipstream technology. Chen proved instrumental in this mission, as she succeeded in communicating with the entity -- naming it Qing Long -- and convincing it to allow the Enterprise to stop the Borg.
During this same time, Chen began a romantic relationship with Ensign Rennan Konya, who had also newly joined the Enterprise crew.
Chen also served as a backup flight controller on the Enterprise. During the Borg Invasion of 2381, she was on bridge duty when the Enterprise destroyed a Borg cube at Korvat. When she expressed relief that the battle was over, Captain Picard insisted that the conflict was merely beginning.
After the discovery of the Borg's subspace tunnels in the Azure Nebula, Chen expressed disagreement with Picard's decision to collapse the passageways, earning her a rebuke from first officer Worf. During the subsequent scouting of the tunnels, the Enterprise encountered a fleet of Hirogen vessels, and Chen saved Aneta Šmrhová from injury from an exploding console, burning her own arm in the process.
After the USS Titan joined the USS Aventine and Enterprise in their fight, Chen was temporarily assigned to assist Lieutenant Commander Melora Pazlar, Chief Science Officer on the Titan, in locating a suitable Borg scout craft to use in order to secure its vinculum. Chen was exceptionally interested in Earth Starfleet Captain Erika Hernandez's experiences amongst the Caeliar, and pestered her with a long series of questions. Hernandez was only partly willing to answer, and only in exchange for the end of Chen's questioning. Hernandez later asked Chen if she made a special effort to confound expectations about her heritage; when Chen confirmed this, Hernandez suggested not trying so hard.
Following the end of the invasion, the Enterprise returned to McKinley Station in Earth orbit, and Chen volunteered to remain aboard as other crewmembers took leave. During this time, she developed a closer friendship with Lieutenant Dina Elfiki, the two engaging in pulling a series of practical jokes on each other. This earned them both the ire of assistant chief engineer Taurik. Following the ship's release from drydock, Chen was recruited to assist the engineering crew in continuing repairs and maintenance. When the Enterprise discovered a lost ship, the SS Libra, carrying thousands of evacuees from the destroyed planet Deneva, Captain Picard assigned Chen as liaison and leader of the Enterprise boarding party. However, during the initial meeting, she erred in assuming the crew was already aware of Deneva's fate, revealing it in an inappropriate manner.
Also shortly after the Borg Invasion, Chen was contacted, for the first time since childhood, by her father, Sylix. He had been seriously injured during the Borg assault on planet Vulcan, and had hoped to contact his former wife, Antigone. Chen dismissed him in a hostile manner. Later, when Chen belatedly learned her mother had been killed in action during the invasion, she contacted Sylix again to give him the news. During that conversation, she left open the possibility of future communication between them.