Template:Sidebar character Deanna Troi was a half-Betazoid, half-Human Starfleet officer. Under the command of Captain Jean-Luc Picard, she served as ship's counselor aboard the USS Enterprise-D and the USS Enterprise-E. In 2379, Troi transferred to the USS Titan. (Star Trek: The Next Generation; Star Trek Nemesis)
As a half-Betazoid, Troi was capable of extra-sensory empathy, but was incapable of reading aliens with brain structures dissimilar to Humans and other Betazoids, like the Breen and the Ferengi. Like most Betazoids, Troi had telepathic abilities; due to her half-Human heritage, however, the range of her telepathic abilities were limited compared to full-blooded Betazoids, and could usually only read the thoughts of other Betazoids, most notably her mother. Troi's empathic skills made her an important asset to the Enterprise and often came in handy when dealing with hostile races. Since she could usually tell if others were lying, she repeatedly proved herself invaluable in many suspenseful situations. (TNG: "Encounter at Farpoint", "Ménage à Troi", "The Loss"; VOY: "Inside Man")
Early life and career
Deanna was born on March 29, 2336, near Lake El'nar on Betazed, to Betazoid Ambassador Lwaxana Troi and Human Starfleet officer Ian Andrew Troi. Deanna was actually the second of their two children, the first being Kestra Troi, born in 2330. Tragically, Kestra drowned when Deanna was just an infant. Stricken with grief and regret, Lwaxana removed all evidence of Kestra's existence from her own life, and even repressed all memories of Kestra. She also made her husband swear never to mention Kestra again. Because of this, Deanna did not learn of her sister until 2370, when Lwaxana's memories resurfaced. (TNG: "Conundrum", "Dark Page")
As required by Betazoid custom, Deanna was genetically bonded with a Human male named Wyatt Miller at a young age. Wyatt was the son of Steven and Victoria Miller, close friends of Deanna's parents. Due to their genetic bonding, Deanna was scheduled to marry Wyatt in adulthood. (TNG: "Haven")
As a child living on Betazed, Deanna often learned aspects of Human culture from her Human father, Ian. One such aspect which he passed on to his daughter was a fondness for stories set during Earth's Ancient West, which he often read to her. (TNG: "A Fistful of Datas") She also heard stories from her maternal grandfather, who told them telepathically; something of a traditionalist, he rarely spoke, saying speech was for "offworlders and people who didn't know any better." (TNG: "Eye of the Beholder")
Deanna frequently felt as though she were the parent and Lwaxana the child. In one instance in 2342, during a party celebrating Deanna's sixth birthday, Lwaxana disappeared halfway through the celebration, but returned later, dressed as a Koropian princess and carried in a sedan chair by four men, much to Deanna's embarrassment. (TNG: "Cost of Living")
Sadly, Deanna's father died in 2343, when Deanna was only seven years old. Even so, she remembered him fondly, and when she became pregnant by an alien energy being, she named the child after her father. (TNG: "Half a Life", "Dark Page", "The Child")
Deanna Troi entered Starfleet Academy in 2355. She later graduated from the Academy in 2359, majoring in psychology. (TNG: "Conundrum") On her homeworld of Betazed, she met William T. Riker, a Starfleet ensign who was stationed on the planet. The two began a relationship sometime between 2357 and 2361 which lasted several years. After Riker was assigned to the USS Potemkin the two planned to spend their holidays together on Risa in 2361. However, Will had to cancel their plans after he was promoted to lieutenant and the couple eventually lost contact to each other. (TNG: "Encounter at Farpoint", "Ménage à Troi", "Second Chances") By 2364, Troi held the rank of lieutenant commander. That year, she was assigned as ship's counselor aboard the USS Enterprise-D. (TNG: "Encounter at Farpoint")
Aboard the USS Enterprise
Troi proved herself to be an important asset to the crew of the Enterprise-D during the ship's first mission to Farpoint Station in 2364. Her ability to sense feelings and emotions gave vital clues which allowed the crew to determine that the station was actually a shapeshifting spaceborne entity being forced into servitude by the Bandi. By rescuing the creature and reuniting it with its mate, Troi and her shipmates were able to pass a test of Humanity's intentions imposed onto them by Q. (TNG: "Encounter at Farpoint")
Soon after, Troi was affected by the polywater intoxication that caused her and the majority of the Enterprise's crew to act out of character, but she was quickly taken to sickbay and provided with medical treatment. (TNG: "The Naked Now") Her empathic abilities came in handy a short time later when she assisted in uncovering the intentions of Ligonian leader Lutan after he kidnapped security chief Natasha Yar. (TNG: "Code of Honor")
When a planet in the Delphi Ardu system drained the Enterprise of its power, Troi and the majority of the ship's crew suffered from exposure to extreme cold and were forced to endure almost deadly oxygen deprivation. (TNG: "The Last Outpost")
Upon first contact with the Ferengi species in 2364, Troi reported that she could discern neither thoughts nor emotions from them, giving her the initial impression that they could shield those from others. She later mentioned, however, that she could sense one of the Ferengi was hiding something. (TNG: "The Last Outpost")
Troi was unable to detect any feelings from the Traveler when he was encountered by the Enterprise's crew in the same year. (TNG: "Where No One Has Gone Before") However, she was later instrumental in discovering that an alien force had been invading the minds of crew members aboard the Enterprise and was influencing Captain Picard, who later temporarily blinded Troi while he was under the alien's influence. After Picard beamed himself and the alien into space, the crew believed that he could not be recovered but Troi sensed that the captain had separated from the alien influence and, thanks to her advice, Picard was ultimately returned safely to the ship. (TNG: "Lonely Among Us")
Later that year, the Enterprise traveled to Haven, a legendarily beautiful planet in the Beta Cassius system. The planet was also the location of Wyatt Miller, who was scheduled to marry Troi due to their genetic bonding. Having expected the marriage would not go ahead due to the distance that serving for years aboard the Enterprise would take her from her homeworld, Deanna initially did not inform her crew mates of her obligation. Nevertheless, she agreed to honor vows taken years earlier, even though she had since become doubtful of them and they necessitated that she leave the ship with her new husband once they had been married. While Deanna's mother, Lwaxana, and both Wyatt Miller's parents were aboard the Enterprise, a social gathering known as a pre-joining announcement was held to celebrate the forthcoming wedding. The marriage itself was permanently canceled, however, when Wyatt, a doctor by profession, chose to join his fantasy lover aboard an infected Tarellian vessel. (TNG: "Haven")
While searching for survivors from the doomed Federation freighter Odin, the Enterprise journeyed to the planet Angel I, becoming the first Federation vessel to visit the planet in sixty-two years. As Angel I was home to a female-dominated society, Troi, who commented early in the visit that a description of the planet made her suspect the location would be very much like her own homeworld, gratefully accepted the offer to make initial contact with the planet's inhabitants and managed to arrange a meeting with a reticent head of government. (TNG: "Angel One")
Later that year, Troi was returning from a conference when her shuttle suffered a sudden instrument malfunction and subsequently crashed on Vagra II. There, a lonely but sadistic entity that referred to itself as Armus held Troi prisoner by surrounding her shuttle with a force field and prevented her crewmates from rescuing her, even going so far as to kill Lieutenant Yar. Troi and her shuttle pilot, Lieutenant Ben Prieto, were eventually rescued after Wesley Crusher and Worf discovered that the field weakened when Armus was provoked. (TNG: "Skin of Evil")
Near the end of her first year aboard the Enterprise, Troi was looking forward to a moonlight swim on the ship's oceanic destination of Pacifica, an experience she believed could not adequately be replicated by the ship's holodeck. She was not provided with the opportunity to enjoy her swim, however, as the Enterprise was diverted to Dytallix B and then to Earth. (TNG: "Conspiracy") Deanna later helped Clare Raymond, a recently revived Human from the late 20th century, learn about her descendants and locate distant relation Thomas Raymond. (TNG: "The Neutral Zone")
In early 2365, Troi became pregnant by an alien who wished to experience Human feelings and relationships. He grew at an accelerated rate and within hours was an eight-year old boy. At the same time, a plasmic plague struck the ship threatening to kill everyone within hours. The alien realized that he was the source of the plague and sacrificed his Human life to save the ship. He reverted back to his alien form and left the ship. Troi experienced both the joy of childbirth and the heartbreak of losing a child. (TNG: "The Child")
The next year she fell for a delegate, Devinoni Ral, at a conference for the rights to a wormhole. Ral and Troi each had an instant attraction for each other. She learned that he was part Betazoid and had been using his mental powers to influence the negotiations. When the Ferengi threatened to blow up the wormhole, stating that there was a secret deal between the Federation and the Barzan, Troi suspected that this was staged by Ral to acquire the rights to the wormhole. The Barzan gave the right to Ral, but it was soon discovered that the wormhole was unstable and worthless. Ral quickly left and bid goodbye to Troi. (TNG: "The Price")
Deanna began studying psychology sometime in the 2350s. While studying at the University of Betazed, one of her patients was Tam Elbrun, a Betazoid male who had been suffering from mental instability due to his lack of the Betazoid's natural ability to "tune out" the thoughts of others. She met him again when he was being transported by the Enterprise to make first contact with an alien lifeform that looked like an organic spaceship. Having lost its crew years ago, Tin Man, as the organism was called, wanted to die and waited by a star that would shortly explode. After boarding the organism, Tam bonded with the alien and remained with it. He had found a way to relieve his mental pain and Tin Man had a companion. (TNG: "Tin Man")
Troi became the object of affection for a new crewmember named Reginald Barclay. He was too shy to approach her so created a holoprogram so he could interact with her. Troi counseled him, and he eventually ended the program. (TNG: "Hollow Pursuits")
While attending a trade conference on Betazed, she, Lwaxana, and Riker were captured by the Ferengi. They wanted to use Lwaxana's telepathic abilities to give them an advantage in negotiations. They used mind probes on Troi and Lwaxana. Riker was able to send a message to Enterprise giving them the location of the Ferengi ship, and they were rescued. (TNG: "Ménage à Troi")
She temporarily lost her powers when she came in contact with two-dimensional lifeforms that had caught the Enterprise in their magnetic force. They were heading for a cosmic string which would destroy the Enterprise. Picard asked her to use her Human abilities to try to determine the aliens' intentions. She found out that the cosmic string was their home; the Enterprise was able to break free, and after the aliens left, her powers returned. (TNG: "The Loss")
While investigating the USS Brattain, which had become stranded in space, the Enterprise found one crewmember alive, a Betazoid science adviser. The rest of the crew had killed each other. They discovered that the ship was caught in Tyken's Rift which sapped all the energy from the ship. Additionally, the crew of the Brattain had succumbed to madness through sleep deprivation from an unknown cause. The same thing was happening to the Enterprise. The crew was on the verge of madness, and only Data and Troi were unaffected, as Data did not require sleep and Troi's partially Betazoid physiology processed dreams at a different frequency. Data believed that an explosion would get them out of the rift, but the plan failed. Troi had experienced a single, recurring nightmare, but determined that it was an act of communication from other beings stuck on the other side of the rift. This communication had caused the dream states of the rest of the crew to become disrupted. In a dream state she relayed a plan of cooperation that would release each ship. The plan worked. (TNG: "Night Terrors")
Troi took command of the Enterprise after it was hit by a quantum filament that caused major damage. The accident trapped the officers in various parts of the ship. Her decision not to separate bridge and engineering and divert power to engineering saved the ship. (TNG: "Disaster")
She counseled Worf and Alexander Rozhenko, who had boarded the ship to stay with his father. Her efforts helped stabilize their relationship. Worf was going to send his son to a Klingon school, but Troi observed that the boy was difficult because of the death of his mother, leaving him a feeling of abandonment. Sending him away would only make the boy worse. (TNG: "New Ground")
During a visit by telepathic aliens, Troi was attacked and lapsed into a coma. On waking, she believed she was attacked by Riker. One of the aliens who participated in the attack had been using his telepathic powers to make her think it was someone else. (TNG: "Violations")
While helping to save a closed society of genetically-engineered Earth colonists, she became romantically involved with their leader, Aaron Conor. After the colony was saved, the romance ended as she returned to the ship and he declined to leave his colony. (TNG: "The Masterpiece Society")
Her body was taken over by an alien spirit after the Enterprise investigated the disappearance of the USS Essex, an event that had occurred almost two hundred years previously. Troi, along with O'Brien and Data, was possessed, and hijacked the Enterprise, taking hostages in the process. The Troi alien stated that he was Bryce Shumar, captain of the Essex, and that he and his crew's spirits were caught up in the magnetic field of the moon. He asked that their bones, which were on the planet, be returned to Earth, so their spirits could rest. Picard did not believe "Troi", and found out that she wished to return to the planet to get the other alien spirits so they could take over the crew's bodies. The moon was a penal colony and the spirits were criminals. After Picard threatened to destroy the Enterprise and their existences, the spirits decided to stay alive on their moon. (TNG: "Power Play")
After boarding the Enterprise and announcing that she planned to marry (again), Lwaxana began to meddle in Troi's attempts to counsel Alexander, Worf's son, about meeting his responsibilities. Deanna also became upset that her mother was not going to follow the traditional Betazed marriage rituals. Lwaxana was suffering a mid-life crisis, and in the end she ended her relationship with her stuffy suitor. (TNG: "Cost of Living")
In 2369, Ves Alkar, a Federation mediator, boarded the Enterprise. Alkar telepathically transferred his dark thoughts and emotions to other hosts so his mind was clear and able to mediate conflicts more effectively. The effect of this transfer caused rapid aging and death. He attacked Troi and Dr. Crusher put her into stasis to save her life. (TNG: "Man of the People")
She participated in an Old West holodeck program with Worf and Alexander that became too real when a malfunction released the safety protocols. They were able to rescue Alexander and put the outlaws in jail. (TNG: "A Fistful of Datas")
In 2369, Troi was kidnapped and surgically altered by the Romulan underground movement. She was forced to assume the role of Major Rakal, an operative for the Tal Shiar, aboard the IRW Khazara. While there, Troi befriended Subcommander N'Vek, who helped her to adopt her role and also revealed the true nature of her mission - help Vice-Proconsul M'ret and two of his aides defect to the Federation. Troi discovered that she wielded much power over the crew of the Khazara, as many people were scared of the Tal Shiar. However, she had a conflicted relationship with the Khazara's commanding officer, Commander Toreth. When Troi's mission took a turn for the worse and a fight with the Enterprise seemed imminent, Deanna seized command of the Khazara. She was able to successfully complete her mission by concealing a transporter beam inside a low-level disruptor blast. N'Vek was killed by the Khazara's helmsman after Toreth re-took command, and the Enterprise barely managed to beam Deanna back on board before the Khazara fled under cloak. (TNG: "Face of the Enemy")
Troi, along with Picard, Data, and La Forge, returned from a conference to find the Enterprise and a Romulan ship suspended in time. This was caused by aliens who were using the warp core as an incubation for their young. After driving out the aliens, the timeline was restored. (TNG: "Timescape")
At the end of the year she engaged Lore and a group of individualized Borg drones. Lore planned to lead them to destroy the Federation and had brainwashed Data into helping him. Troi, Picard, and La Forge were captured by Lore. They stole a transceiver that they used to restore Data's ethics. They were rescued by Hugh, Data, and the Enterprise. (TNG: "Descent", "Descent, Part II")
In early 2370, a group of aliens boarded the Enterprise as part of a cultural exchange. Troi was the liaison for Loquel. He drove her crazy, as all he wanted to do was indulge himself and party. It was revealed that his assignment was to experience pleasure. (TNG: "Liaisons")
Troi attempted the Bridge Officer's test in 2370. Riker supervised the tests, and did not show any favoritism towards Deanna. After she attempted the engineering qualification several times without much luck, he told her the tests were canceled. However, he also gave her a hint which told her that the test was really about her ability to send a crewmember to his death. (TNG: "Thine Own Self")
She helped save her mother's life when Lwaxana was suffering a severe mental breakdown due to a long repressed memory. With the help of a telepathic alien, she was able to enter into her mother's mind and find the source of the mental trauma. Troi found out she had a older sister who died in a drowning accident that Lwaxana blamed herself for. She was able to help her mother accept the death and convince her that she was not to blame. (TNG: "Dark Page")
After a crewmember, Daniel Kwan, committed suicide on board the Enterprise, Troi was asked to investigate, since the crewman had empathic abilities and Troi might be able to find out why he killed himself. After examining his station, Troi became insanely jealous of Worf and when she found him in the arms of another female crewmate, she killed him and attempted suicide. As she prepared to jump to her death, Worf, who was actually still alive, saved her. It turned out that everything that she experienced was in her mind. When the Enterprise-D was being built, one of the crew, who had been an empath, committed murder and suicide, and this empathic message was picked up by Kwan, leading to his death. Troi picked up the same message, but was more fortunate. (TNG: "Eye of the Beholder")
In 2371, Troi piloted the Enterprise-D during the Battle of Veridian III and the subsequent crash-landing of the ship's primary hull on the planet below. She was the last person to pilot the ship, as the engineering section was destroyed due to a warp core breach and the saucer section could not be salvaged. (Star Trek Generations)
- "Skin of Evil"
- "The Child"
- "The Price"
- "Tin Man"
- "Ménage à Troi"
- "The Loss"
- "First Contact"
- "Half a Life"
- "The Mind's Eye"
- "Cost of Living"
- "Man of the People"
- "Chain of Command, Part I"
- "Chain of Command, Part II"
- "Face of the Enemy"
- "Dark Page"
- "Thine Own Self"
- "Eye of the Beholder"
- Star Trek films:
In 2372, Deanna transferred to the Template:ShipClass USS Enterprise-E, with most of the senior staff of the Enterprise-D. The following year, she and her fellow crewmates disobeyed Starfleet orders by taking part in the Battle of Sector 001. The Enterprise was instrumental in the destruction of an invading Borg cube but pursued a remaining Borg sphere back in time to 2063, subsequently destroying the Borg craft before it could prevent the historic first flight of Zefram Cochrane's Phoenix warp ship.
After the Borg attack, two teams of officers beamed to the surface of Earth, with Deanna serving as a member of the second team. She struggled to search for Zefram Cochrane on the planet and accepted a civilian's offer of a drink in return for information. After three shots of tequila, Troi, having become extremely drunk, eventually found out that the civilian was actually Zefram Cochrane himself. After she and the inventor were found in a bar by Riker, Troi continued to share a drink of extremely strong tequila with Zefram Cochrane, who she officially reported was "nuts", before losing consciousness due to her large consumption of alcohol.
After she came to, Troi helped to convince Cochrane of the importance of his first warp flight, as he considered canceling it following the Borg attack. Troi also supervised the historic launch of the Phoenix from Earth and assisted in preserving the subsequent first contact between Humans and Vulcans. A few seconds before launch, Zefram blasted Magic Carpet Ride in her ear. (Star Trek: First Contact)
Two years later, in 2375, Troi helped Captain Picard prepare to host a reception for a visiting delegation of Evora representatives - after having read a Starfleet report on their species - and later attended the ceremony with Picard, Riker and Dr. Crusher. Later, Troi alone downloaded all Starfleet records on the Son'a and studied them with Riker. Troi was also in command of the bridge right before the Enterprise-E arrived at the Briar Patch. Upon encountering members of the Ba'ku who the Son'a had been observing until recently, Deanna used her telepathic abilities to sense that several Ba'ku children present had incredible mental discipline and clarity of perception.
After it was learned that the Son'a were attempting to discreetly relocate the Ba'ku from their homeworld, Troi helped to evacuate the Ba'ku from their village to the safety of a mountain range. Around this time, she noticed that her breasts had started to firm up, a result of the age-decelarating properties of metaphasic radiation in the planet's rings. She also helped eliminate Son'a drones but, after Picard and a Ba'ku woman became trapped following a cave-in, her plan to cut away rock using her phaser was not used as it was thought to be too potentially dangerous. Once the two imprisoned humanoids were released, Troi stayed with the refugees as most of the other senior officers left to successfully prevent the Son'a from relocating the Ba'ku, who were actually their own distant relations. (Star Trek: Insurrection)
In 2379, Deanna made her final voyage aboard the Enterprise as the ship journeyed to Romulan space on a diplomatic mission in which she and her crewmates met the new Reman Praetor, Shinzon. Aboard the Enterprise, Troi was telepathically violated by Shinzon, who seemed obsessed by her. She used their residual link to her advantage, however, during the Battle in the Bassen Rift; after the Enterprise was nearly disabled, Troi took the helm and, under Captain Picard's orders, crashed the ship into the Scimitar, further disabling Shinzon's Reman warbird. Deanna was later saddened to learn that the fatalities of the battle included not only Shinzon but also Data. She subsequently joined the USS Titan, under Riker's command, and was due to return to Romulus on another diplomatic mission. (Star Trek Nemesis)
In 2376, Deanna Troi visited Lieutenant Reginald Barclay while she was enjoying shore leave on Earth. Barclay, an old friend of hers from the Enterprise-D and -E, told her about his role in the Pathfinder Project - a mission to determine a method of communicating with the USS Voyager, stranded in the distant Delta Quadrant. Using a holographic simulation of the starship and its crew, Barclay had devised a plan to contact Voyager. However, he had become obsessed with the starship and Troi feared that he was suffering from a relapse of holo-addiction, a condition he had previously recovered from with Deanna's assistance. Although Troi was scheduled to leave Earth aboard the Enterprise the next morning, she decided to ask Captain Picard for a temporary leave of absence so that she could spend some time with Barclay. Later that night, Barclay left his apartment and headed to Starfleet Command, where he finally managed to establish communication with Voyager. Deanna later shared a drink with Barclay to celebrate his success. (VOY: "Pathfinder")
In 2377, Troi was serving aboard the Enterprise when Barclay contacted her from Jupiter Station. His friend and the inventor of the Emergency Medical Hologram, Doctor Lewis Zimmerman, was terminally ill on Jupiter Station and only expected to live a few more months. The officers aboard Voyager had managed to send a member of their crew, a Mark I EMH named simply The Doctor, to Jupiter Station but Dr. Zimmerman was refusing to be treated by The Doctor, whom he saw as inferior to the later Mark III and Mark IV EMHs.
Barclay suspected that Troi might be able to persuade Zimmerman to allow The Doctor to cure him before he died. Although the Enterprise was in the middle of a mission almost seven light years away, Troi agreed that the plan sounded like an interesting challenge and requested leave from Captain Picard. A week later, she arrived at Jupiter Station but was unable to mediate an agreement between the two doctors. Zimmerman and The Doctor ultimately reached a mutual understanding without Troi's help. (VOY: "Life Line")
Later that year, Troi was sunbathing on a beach when Barclay crept up on her. He told her that he had created an advanced interactive hologram in his own image with the express purpose of sending it to Voyager, but the program had gone missing on its way to the starship. Troi helped Barclay and his supervisors at the Pathfinder Project to determine that the crew of a Ferengi casino ship had stolen the hologram. Troi and Barclay discovered that the Ferengi had reprogrammed the hologram and sent it to Voyager in an attempt to acquire Borg nanoprobes from Seven of Nine. The casino ship opened a geodesic fold, a gateway to the Delta Quadrant. Troi suggested sending a warning message to Voyager through the geodesic fold but Barclay told her that subspace transmissions could not pass through the anomaly.
Instead, Barclay contacted the casino ship from the Voyager simulation at Starfleet Command while Troi stood next to him and watched from out of the Ferengi's view. Pretending to be his hologram, Barclay told the Ferengi that Captain Janeway had discovered their plan and was furiously preparing to attack with powerful weaponry. The Ferengi believed the trick and closed the geodesic fold. Shortly before Deanna left San Francisco, Barclay was working on programming another version of his hologram with security protocols so it couldn't be stolen again. (VOY: "Inside Man")
In 2379, Deanna married Will Riker. The first ceremony was a traditional Earth wedding, where Captain Picard served as Will's best man. After that ceremony, a traditional Betazoid wedding ceremony was to take place on Betazed. However the Enterprise-E's journey to Betazed was interrupted by the discovery of B-4. (Star Trek Nemesis)
Deanna and Beverly often advised one another on romantic relationships. Deanna worried that her romance with Devinoni Ral was proceeding too fast, but Beverly assured her that perhaps she did not need to be rational regarding a whirlwind romance. (TNG: "The Price")
Crusher did not often use the salon aboard the Enterprise, and began to do so when she began a relationship with Odan. Deanna arrived at the salon around the same time, and Beverly became self-conscious. Troi recognized the feelings between Odan and Beverly, even though the two tried to keep their romance a secret, and liked seeing Crusher happy. However, Troi also sensed the dual nature of the ambassador, and warned Beverly to be cautious. Later, when Odan was implanted in Will Riker's body, Deanna counseled Beverly on the mixed feelings she then felt towards Odan. Although Beverly wished she had never met him, Deanna told Beverly that she could never love without risking pain and encouraged Beverly to accept Odan's love if she still felt it while he was in Riker's body. (TNG: "The Host")
In 2369, the Enterprise rescued a transporter-created duplicate of Will Riker, known as Thomas Riker, from the research station on Nervala IV. Tom Riker wished to resume the romantic relationship he had with Deanna, which Will Riker had broken off upon the mission to Nervala. Troi and Crusher discussed a date with Tom during a workout, where Crusher mischievously pointed out that Troi should not be afraid to try a relationship with the duplicate Riker. When Tom Riker entered the gym, Beverly decided to leave the two alone, which led to Tom and Deanna becoming intimate. (TNG: "Second Chances")
Deanna accompanied Beverly to Felisa Howard's funeral in 2370, and went with her back to Felisa's home following the services. Beverly confided to Deanna about the erotic dreams she experienced after reading her grandmother's journals, which were due to the influence of Ronin. After Beverly met Ronin on Caldos, Deanna reminded her that her feelings of romance may simply be due to shared trauma, but Beverly brushed off her concern. (TNG: "Sub Rosa")
Troi's relationship with Reginald Barclay did not start off very well. Because he was intimidated not only by Troi's beauty but by her status as ship's counselor, he even went as far as to meet with a holographic version of her rather than meet with the real Troi. In Barclay's holoprogram of The Three Musketeers with the senior staff serving the primary roles, Troi told Riker and La Forge that there was nothing wrong with a healthy fantasy life until she found her likeness was the Goddess of Empathy. After this incident she began a real world counseling relationship with Barclay, including helping him through his bout of transporter phobia. (TNG: "Hollow Pursuits", "Realm of Fear")
While infected with the polywater intoxication, Yar came to Troi's quarters later that year in need of advice regarding her hair and clothes. Even though the lieutenant seemed playfully content, Troi sensed that she was actually very uncertain and was fighting something. Concerned for her crewmate and friend, Deanna asked Yar what was wrong and, after the lieutenant left without answering the question, immediately reported her strange behavior to Captain Picard. Unknown to Troi at the time, however, she herself had contracted the polywater intoxication from Yar during their brief encounter. (TNG: "The Naked Now")
After Yar was kidnapped by Ligonian leader Lutan, Troi helped in uncovering the intentions of her friend's captor, remarking at one point that she believed Yar was physically very attractive. After Lutan announced his decision to make Yar his First One, Deanna tricked the lieutenant into admitting, in the presence of Captain Picard, that she had felt good when Lutan had said he wanted her. Troi's deceit shocked Yar, as she regarded Deanna as a friend, but the counselor explained that she had used deception only so that Yar would answer honestly how she felt about Lutan. Troi later argued in favor of Yar partaking in a fight to the death against a challenger to her entitlement, advising Picard that the lieutenant would easily be able to beat her opponent - Lutan's current First One, Yareena. (TNG: "Code of Honor")
Deanna had a tense relationship with her mother. She felt at times that she was the mother and Lwaxana was the child. She was often visibly irritated when her mother showed up to the USS Enterprise-D unannounced. Lwaxana was also often more concerned with her daughter's love life than Deanna herself was. (TNG: "Haven", "Ménage à Troi")
Ian Andrew Troi
Ian Troi died in 2343 when Deanna was around seven years old. She was devastated by his sudden death. Deanna remembered him fondly years later. When she became pregnant by an alien energy being, she named the resulting child after her father. (TNG: "Half a Life", "The Child")
Kestra Troi was Deanna's older sister. However, Deanna did not know of Kestra until 2370 when she was visited by Lwaxana Troi, who was invited to the Enterprise to be an telepathic interpreter for a group of Cairn delegates. The Cairn, along with a Cairn child, Hedril, who reminded Lwaxana so much of Kestra, caused so much strain on Lwaxana that her brain shut down. It was later revealed that Kestra tragically died from drowning during a family picnic when Deanna was a baby. Lwaxana, instead of dealing with the loss, buried the memory until this event with the Cairn. (TNG: "Dark Page")
William T. Riker
Deanna had an intimately close relationship with Will Riker, occassionally referring to him as imzadi, a Betazoid word for "beloved". Before they served together on the Enterprise-D, Troi taught Riker how to read her thoughts when she telepathically projected them. They learned each other's abilities but couldn't say "goodbye" when they parted.
After Troi was assigned to the Enterprise-D in 2364, she was reunited with Riker. Although they informed Captain Picard that they already knew each other, neither Riker nor Troi initially revealed the intimate nature of their former relationship. Troi seemed fairly eager to be alone with Riker and, while at Deneb IV's mysterious Farpoint station, she suggested that they explore the passages below the station together, an idea that Riker refused. Before he later endangered his own life to investigate why a spaceborne entity believed to be a ship was attacking Deneb IV, Troi expressed, in an outburst of emotion, her extreme fear that Riker could be hurt. She soon managed to resume her former sense of calm, however, and returned to the Enterprise as Riker had ordered. (TNG: "Encounter at Farpoint")
While under the influence of polywater intoxication, Troi was drawn to Riker and, in an attempt to seduce her former lover, she sensuously embraced him in a hug in engineering. When he picked her up in his arms and began carrying her to sickbay, she asked if he wouldn't rather be alone with her in his mind than ensuring she was hospitalized. Riker, however, did not surrender to her seductive advances and succeeded in taking her to sickbay. (TNG: "The Naked Now")
Troi and Riker were later asked by Captain Picard to exhibit use of the Enterprise's holodecks to a party of Ligonian representatives, while they were negotiating with the ship's crew upon visiting the vessel. When Ligonian leader Lutan instead requested that Lieutenant Yar demonstrate defense training in one of the holodecks, Picard's request went unanswered and Troi lost the opportunity to work solely with Riker. (TNG: "Code of Honor")
Troi's life, as well as the lives of virtually the entire crew of the Enterprise, was later saved by Riker when he managed to persuade Portal 63 of the long-extinct Tkon Empire to release the starship from his control, as the Portal had trapped the Enterprise in an energy field that was draining the ship's power and forcing its crew, including Troi, to endure extreme cold and almost deadly oxygen deprivation. (TNG: "The Last Outpost")
During the Enterprise-E's mission to Ba'ku in 2375, Deanna and Will were affected by the metaphasic radiation of the planet's rings, which eventually led to them reviving their relationship. (Star Trek: Insurrection)
Worf was distrustful and uneasy around telepaths, but Troi became a trusted exception. When he was severely injured in 2368, he asked her to care for Alexander if he died. By late 2370, Worf asked her to become a soh-chim to Alexander, a role she gladly accepted. (TNG: "Dark Page", "Ethics", "Parallels")
After an encounter with alternate realities showed him a life with Troi as his wife, Worf's eyes were opened to a new possibility, he began to pursue her. Though surprised, Troi welcomed the advances, and the two enjoyed a romantic relationship through 2370. Deanna wasn't thrilled by Worf's concern for Will Riker's interest in the matter, but the triangle's tension was eased by the advice of Captain Picard. (TNG: "Parallels", "Eye of the Beholder", "All Good Things...")
By the next year, the romance seemed to have dissolved amicably, and eventually, she and Riker resumed their relationship. Worf's only visible unease at their wedding in 2379 was the result of imbibing too much Romulan ale, and the prospect of appearing naked at their Betazed marriage ceremony. (Star Trek Generations; Star Trek: Insurrection; Star Trek Nemesis)
Alternate realities and timelines
In an alternate timeline briefly created in 2366, Deanna Troi was not serving as a senior officer aboard the Enterprise-D when the ship encountered its predecessor, the Template:ShipClass starship USS Enterprise-C. (TNG: "Yesterday's Enterprise")
In 2369, Q sent Captain Picard into an alternate timeline in which he was a mere lieutenant jg assigned to the Enterprise-D as an assistant astrophysics officer. Although Troi and the other senior officers were less familiar with Picard than they were in his own universe, she and Riker provided advice he sought from them regarding his career prospects. Deanna was eager to leave the meeting, believing that Ten Forward was not the best place to have their discussion, but, shortly before leaving the room with Riker, she suggested to Picard that they meet later to resume their conversation. (TNG: "Tapestry")
In 2370, Lieutenant Worf encountered a quantum fissure that caused him to begin shifting between quantum realities. In at least one universe, Troi participated in a surprise celebration for Worf's birthday. Later, Troi spoke with Worf about his son, Alexander, and graciously accepted his offer to serve as his son's soh-chim, formalizing her motherly relationship with Alexander. In two other universes that Worf visited, he was married to Troi in an extremely loving relationship. In the first of those universes, Deanna's romantic affiliation with Worf had begun approximately three years earlier, after he had sought Riker's formal permission to court Troi in the belief that to do otherwise would be dishonorable. In the latter of the two universes in which Troi was married to Worf, the Klingon was first officer and father of two children with Troi. They had a son named Eric-Christopher, who was born in 2367, and a daughter named Shannara, who was born in 2368. However, Troi had no knowledge of Worf's son, Alexander. Although she believed that the Worf who was indigenous to her own universe might not return, Troi kissed Worf goodbye before the Klingon departed her ship in the Curie, a type-6 shuttlecraft. (TNG: "Parallels")
In an unknown, alternate future timeframe, Troi died from unknown causes, and a funeral was held in her memory. Both Worf and Riker were extremely saddened by her demise and blamed the other for preventing a relationship with her, causing relations between the two men to become deliberately estranged for the next twenty years. (TNG: "All Good Things...")
Deanna Troi has been holographically duplicated on a number of occasions.
- In 2366, Reginald Barclay, while suffering from holo-addiction, created at least two holographic characters based on Troi in his holodeck fantasy worlds. One referred to itself as the Goddess of Empathy and wore a toga-like garment while displaying aggressively flirtatious and exhibitionist tendencies.(TNG: "Hollow Pursuits")
- In 2367, Barash trapped Riker in a holographic illusion set in the year 2383. The illusory Troi had similarities and differences to the actual Troi, looking older but acting as if she could still sense the feelings of others. Having supposedly accepted a position at Starfleet Command offered to her by "Admiral" Picard, the fictional Troi held a commander's rank and served as Picard's aide, no longer assigned to the Enterprise-D. As the Federation was on the verge of signing a peace treaty with the Romulans, Troi accompanied Admiral Picard aboard the IRW Decius, a Romulan Warbird that also carried Ambassador Tomalak, from Romulan space to the Enterprise. In a conversation with Riker, Troi spoke highly of "Min", the now-deceased woman who had married him and had replaced her as ship's counselor following her departure from the Enterprise. However, after Riker discovered that the woman Troi had referred to was apparently Minuet (a holographic fantasy character he had once created), Troi tried to prevent him from angrily demonstrating the errors of the illusion by encouraging him to become calm. The illusion ended shortly thereafter. (TNG: "Future Imperfect")
- In 2369, a hologram of Troi was created by James Moriarty as part of a holographic illusion to trick Captain Picard into releasing his control over the Enterprise-D. (TNG: "Ship in a Bottle")
Among the holographic environments that Deanna Troi visited are sickbay and engineering aboard the Template:ShipClass starship Voyager, and the bridge, captain's ready room and engineering aboard the NX class starship Enterprise. (VOY: "Life Line", "Inside Man"; ENT: "These Are the Voyages...")
Troi frequently wore nonuniform attire while on duty, possibly due to her position as ship's counselor. She primarily favored unitards in a variety of colors, as well as one turquoise variant with a long skirt. However, while serving under Edward Jellico in 2369, she was ordered to wear a standard duty uniform, which she continued to use after Captain Picard resumed command. (TNG: "Chain of Command, Part I")
Troi was able to beat Data in a game of three-dimensional chess, using "intuition". When faced with the Kriskov Gambit, instead of countering with the el-Mitra Exchange as is characteristic, Troi chose to leave her king vulnerable, devising a completely unanticipated response to a classic attack, and forcing checkmate in seven moves. (TNG: "Conundrum")
- 2336: Born on Betazed to Ian and Lwaxana Troi
- 2336: Older sister, Kestra, drowns
- 2343: Father, Ian Andrew Troi, dies
- 2350s: Begins studying psychology at the University of Betazed
- 2359: Meets and begins relationship with Starfleet officer William T. Riker
- 2359: Graduates from Starfleet Academy
- 2361: Breaks off romantic relationship with William Riker
- 2364: As Starfleet officer with rank of lieutenant commander, assigned aboard USS Enterprise-D as ship's counselor
- 2364: Prearranged marriage to Wyatt Miller is called off
- 2365: Son, Ian Troi, is born and dies
- 2370: Promoted to rank of commander after passing the Bridge Officer's Test
- 2371: Successfully pilots the Enterprise-D's saucer section safely into Veridian III after being knocked into the atmosphere by the exploding stardrive section with all hands alive
- 2372: Assigned as ship's counselor aboard USS Enterprise-E
- 2375: Rekindles romantic relationship with William Riker
- 2379: Married to William Riker in ceremonies held on Earth and later on Betazed
- 2379: Transfers aboard USS Titan with William Riker
- All episodes except for "Hide and Q", "Datalore", "11001001", "Heart of Glory", "A Matter Of Honor", "The Perfect Mate" and "The Inner Light"
- Star Trek Generations
- Star Trek: First Contact
- Star Trek: Insurrection
- Star Trek Nemesis
- ENT: "These Are the Voyages..."
- Deanna Troi was played by actress Marina Sirtis. The baby Deanna Troi in "Dark Page" was played by an unknown infant.
- Deanna's birthday was seen on the screen as being March 29th, which happens to be Sirtis' real birth date. (TNG: "Conundrum")
- The original concept for the character of Deanna Troi had much in common with the Ilia character, created for the abandoned series Star Trek: Phase II before ultimately appearing in Star Trek: The Motion Picture. Similarly, Troi's relationship with Riker has its conceptual roots in Ilia's relationship with Willard Decker from Star Trek: The Motion Picture.
- According to the Star Trek: The Next Generation Companion, Troi's description in the original casting call was as follows:
- LT. DEANNA TROI – An alien woman who is tall (5'8-6') and slender, about 30 years old and quite beautiful. She serves as the starship's Chief Psychologist, Deanna is probably foreign (anywhere from Italian, Greek, Hungarian, Russian, Icelandic, etc.) with looks and accent to match. She and Number One are romantically involved. Her alien "look" is still to be determined.
- Notably, Troi's alien roots are not fully detailed in this description but she was described in the first version of the series "bible" as only a quarter Betazoid with some telepathic powers due to her "Starfleet officer grandfather having lived on Betazed with one of its humanoid females". In the final draft of the writer's guide to the series (most likely with the script for "Haven" under development), Troi's heritage was altered to how it is established in the series - half Betazoid, with her Starfleet father having lived on Betazed with her native mother. In early brainstorming, the character was to have three breasts, but this was objected to by D.C. Fontana. 
- Troi's position in one of the Enterprise-D's three center seats, the other two chairs occupied by Picard and Riker, was originally to have been filled by Data. This was changed when the producers realized that Troi would be strengthened both in her shipboard role and as a character if she were to occupy the third central seat. Troi was also given the informal duty of notifying Picard of the concerns of his thousand-plus crew, a duty that was initially the official responsibility of Geordi La Forge.
- Denise Crosby was originally intended to play Deanna Troi, while Marina Sirtis was auditioning for the role of Macha Hernandez (later to be named Natasha Yar). Although producers Robert Justman and Rick Berman were happy with this arrangement, Gene Roddenberry decided that each actress would be better as the other's character and the roles were consequently reversed.
- Before the pilot episode was made, Troi's rank was changed from lieutenant to lieutenant commander, ultimately established by a bridge monitor that appears in "Code of Honor". However, during an away team mission in "Encounter at Farpoint", Riker mistakenly refers to Troi as "lieutenant", carried over from an earlier version of the script. Although Picard refers to Troi as "commander" in the very first scene, she is not referred to as holding that rank in any other episode of the first season. Indeed, "Encounter at Farpoint" is the only time Troi wears a uniform with rank insignia for the first half of the TNG series, until "Chain of Command, Part I" (although a fictional depiction of a uniformed Troi appeared in "Future Imperfect"). It wasn't until "Disaster" and "Conundrum" that her lieutenant commander rank would be mentioned again, however it would be seen on the observation room viewscreen when Dr. Pulaski showed an image of her unborn foetus in "The Child".
- Several other differences exist between the pilot episode's depiction of Troi and her appearance in the subsequent series. These include the fact that she communicates telepathically with Riker in the pilot, but does not do so in the series, a lessening of her abilities that essentially avoided the emotional soliloquies that even made actress Marina Sirtis cringe in "Encounter at Farpoint".
- Other differences were changes in Troi's hair and clothing - she wears a virtually unique "skant" version of the Starfleet uniform in "Encounter at Farpoint", but is mostly adorned in civilian attire in the series; she wears her hair up in a perm in the pilot, but appears with a severe bun hairstyle throughout the first season. An unused look considered for the character included the old "skant" Starfleet uniform and the later used severe bob hairstyle. These changes were a result of the belief that Troi had looked too "loose" and too cheerleader-like in "Encounter at Farpoint".
- As the first season progressed, the writers struggled with Troi's character, believing her to be one of the hardest to write for. According to actress Marina Sirtis, Troi was almost even dropped from the series after she was unused in four episodes.
- Deanna Troi was the first counselor to appear in a Star Trek series and would ultimately become the most prominent example of that role in the franchise.
- Troi is one of four characters to appear in two series finales, (TNG: "All Good Things..." and ENT: "These Are the Voyages...") the others being William T. Riker, Worf, and Miles O'Brien.
- A wig, believed to be worn by Marina Sirtis or one of her doubles in the latter films, was sold off on the It's A Wrap! sale and auction on eBay. 
In the novel Triangle: Imzadi II, set in mid-2371, Worf makes a marriage proposal to Troi and she accepts. However, after Riker and Commander Elizabeth Shelby rescue Troi and Worf's son, Alexander, from a hostage situation, Troi and Worf realize that they are too different to be married and that Troi still has feelings for Riker. The couple call off their engagement as a result.