"Laws change depending on who's making them, but justice is justice."
Odo was a Changeling, one of a hundred infants sent out to explore the galaxy and compelled to return later in order to share their experiences. He served as chief of security aboard the space station Terok Nor, later known as Deep Space 9.
Odo was one of the "Hundred Changelings", a group of one hundred newly-formed Changelings that the Founders sent out in order to gather information and explore and did not expect to return until the late-27th century. (DS9: "The Search, Part II", "Chimera")
In 2337, Odo was found adrift in his natural gelatinous state in the Denorios belt in the Bajoran system. 19 years later, in 2356, he was brought to the Bajoran Institute for Science to be studied by Doctor Mora Pol. Not initially recognizing Odo as a sentient being, Mora subjected him to a long series of experiments, in which Odo endured time in a vacuum chamber and a protein decompiler, as well as extensive electric shocks. Odo eventually rebelled against Mora's unintentional mistreatment by forming into a tentacle and hitting him, (DS9: "Emissary", "The Begotten") before later forcing Mora to recognize him as sentient by copying a beaker on a laboratory table. (DS9: "The Alternate")
Mora continued to study and teach Odo during the Occupation of Bajor, assisted by Dr. Weld Ram. When Odo assumed humanoid form, he copied Dr. Mora's hairstyle. During the Occupation of Bajor, Odo performed a Cardassian neck trick that greatly amused the Cardassian officers. When Odo left Dr. Mora's institute, he did not leave on good terms. He resented some of the methods Mora had used on him, and blamed him for not realizing that he was sentient. (DS9: "Necessary Evil", "The Alternate")
His name stems from the Cardassian word for "nothing," Odo'ital, which was mistranslation of the "Unknown sample" label on his laboratory flask. The Bajoran scientists nicknamed him "Odo Ital" as if it were a Bajoran name, and it was shortened to Odo. (DS9: "Heart of Stone") He used only the single name "Odo." (DS9: "The Forsaken") Early in his life, when he heard others address him as "Odo", he heard it as "nothing." He felt that the name was appropriate, since he had no friends, no past, and no form; once he had gained the respect and affection of Kira and the others on the station, he ceased hearing "Odo" as "nothing" and simply considered it his name. (DS9: "Heart of Stone")
At some point during the occupation, Odo arrived on Terok Nor. He was seen as an impartial outside observer, and often settled disputes between the Bajoran workers on the station. In 2365, due to his reputed neutral position, Odo was recruited by Gul Dukat to investigate the murder of a Bajoran collaborator. Among his chief suspects was Kira Nerys. Odo was able to discover that she was a Bajoran resistance fighter. He, at that time, lied to Dukat and did not reveal her identity. He discovered in 2370 that she was indeed the murderer. In their initial encounter, Kira sardonically called Odo "Constable", a term she later adopted as a term of affection, and which eventually fell into common use as an unofficial title. (DS9: "Necessary Evil")
Odo continued working for the Cardassians, eventually becoming chief of security.
In 2366, Odo investigated an assassination attempt (a bombing) on Dukat. Three Bajoran workers were initially linked to the attack, and Odo– too concerned with maintaining order and the rule of law– hurriedly convicted them and allowed them to be executed. If he had performed any kind of investigation instead of relying on circumstantial evidence, he would have seen that the three men were clearly innocent. However, he didn't know the difference between "order" and "justice" at that time.
A bombing identical to the one that nearly killed Dukat occurred three days later, and he realized the men were innocent and that his lax investigative procedures caused a serious miscarriage of justice. This incident prompted Odo to be much more insistent on actual justice, though not necessarily the actual letter of the law. His guilt was revealed when after traveling through a plasma storm, his mind formed a link with the other passengers and caused them to relive what had happened seven years prior, the four taking on the roles of the convicted men and an unidentified Bajoran woman in a hallucination of the past (DS9: "Things Past").
It was quite clear that his Cardassian employers still viewed him with suspicion; an automated counter-insurgency program designed to activate in the event of a slave revolt on the station was programmed to raise a force field around Odo's office on the assumption that he would shift sides to aid the insurgents. (DS9: "Civil Defense")
As an investigator in a totalitarian regime, Odo was occasionally required to operate outside official channels, and maintained a clandestine network of debts and allegiances to high-ranking members of the Cardassian government he could call on when needed. In the course of his career, he developed an extensive knowledge of espionage and assassination techniques, such as poison, explosives and scrambling signals. (DS9: "Improbable Cause")
Deep Space 9
Chief of security
He retained his post as chief of security even after the withdrawal of the Cardassian forces, when the station fell under Federation administration and was renamed Deep Space 9. At first, Odo and Benjamin Sisko did not see eye-to-eye on how station security should be handled, but eventually they became close associates. (DS9: "Things Past", "Emissary") Sisko stood by him when he was accused of killing a Bajoran he had arrested years earlier. When the Bajorans on the station became unruly and wanted to harm him, Sisko protected him. The situation was resolved when it was discovered that the Bajoran, Ibudan, had faked his own death in order to take revenge on Odo. (DS9: "A Man Alone")
Having been found in the Denorios belt, the discovery of the Bajoran wormhole provided him with further opportunity to investigate his origins. He was tricked by Croden into believing he had discovered Odo's people. The story had been fabricated by Croden to get Odo's help in rescuing Croden's daughter. Croden apologized to Odo for the deception and wished him luck in finding his people. (DS9: "Vortex")
Odo resolved the conflict between Kira, who threatened mutiny, and Sisko, who wanted to arrest her for treason. Both were affected by a matrix that contained a log of a similar battle in an ancient culture, causing the crew to do the same thing. Fortunately, Odo's non-organic nature rendered him immune to it, and with the aid of Doctor Bashir, he was able to remove the sphere's influence, and eject it out of a cargo bay door. (DS9: "Dramatis Personae")
His investigation of a Cardassian claiming to be Darhe'el, a war criminal, proved that the man was actually Aamin Marritza, a file clerk for Darhe'el who wanted the Cardassian people to realize their crimes. (DS9: "Duet")
In 2370, an extremist group of Bajorans, known as the Circle, led by Minister Jaro Essa and supported by Vedek Winn Adami, demanded that all non-Bajorans leave DS9 and Bajor. Civil war threatened the planet, but Quark informed Odo that the Circle was being helped and financed by Cardassia in order to drive out the Federation, leaving the planet ripe for re-conquest. The weapons had been smuggled to the Circle through Kressari traders, which Odo revealed by using his shapeshifting abilities to "borrow" a manifest with a gul's thumbscan on it. (DS9: "The Homecoming", "The Circle", "The Siege")
Odo and Dax, while in the Gamma Quadrant, discovered a planet where the people were disappearing. The people were actually holograms created by Rurigan, the sole survivor of a planet destroyed by the Jem'Hadar. Odo and Dax fixed the holo-generator and restored the people. In the process, Odo formed an attachment to a little girl called Taya, even shifting into a top for her amusement before he and Dax departed. (DS9: "Shadowplay")
He helped represent Miles O'Brien in a Cardassian court on fake charges of aiding the Maquis. His knowledge of Cardassian law annoyed the court, and his delaying tactics provided time for Sisko to prove the evidence false, and gain O'Brien's release. (DS9: "Tribunal")
During a mission to locate the Founders of the Dominion in the Gamma Quadrant, he found himself drawn to a rogue planet in the Omarion Nebula. There he discovered that the Founders were, in fact, Changelings like himself. After initially becoming annoyed with shifting into every plant and rock he could see, with the aid of the Female Changeling, he changed into a bird and took flight, finding that he enjoyed exploring his shape-shifting abilities. He soon discovered their distrust of "solids", though, and rejected them in favor of his friends. (DS9: "The Search, Part I", "The Search, Part II")
Later that year, he had another encounter with the Founders. Kira and Odo were on an away mission. They land on a planet to answer a distress call that seems to come from a Maquis Raider. While on the planet, Kira is captured and the Female Changeling assumed the appearance of Kira. The Changeling pretended that she was trapped inside a growing crystal that was suffocating her. When Odo admitted his feelings for Kira, he was subsequently able to see through the ruse when she claimed to feel the same way; he was sure that Kira didn't love him, but knew she wouldn't lie to him about something so important. It gave the Changeling an understanding of Odo's feelings for Kira, although Odo still refused to admit how he felt to the real Kira. (DS9: "Heart of Stone")
He also served as host for Curzon Dax during Jadzia Dax's Trill zhian'tara, shifting into a form resembling Curzon. Initially, the two wanted to stay together, but Curzon was eventually convinced to return to the Dax symbiont. This gave Jadzia a greater understanding of the joy Odo found in his shape-shifting abilities and Odo learned about how much fun solids had staying up all night drinking and playing Tongo. (DS9: "Facets")
In 2371, a newly "born" Jem'Hadar was found among the wreckage of a salvaged ship Quark had purchased. The baby matured into an adolescent within days, and as a Changeling (and therefore a Founder in the boy's eyes), Odo inherited the responsibility of looking after him.
The Jem'Hadar was willing to do literally anything Odo asked of him. Odo tried to break the boy of this habit and encouraged him to think for himself and resist his natural-born tendencies toward violence. Ultimately, the boy decided that he belonged with the other Jem'Hadar and that anyone who was not Jem'Hadar was his enemy. Odo, wanting to protect the crew, escorted the boy to Dominion space. (DS9: "The Abandoned")
Also in 2371, Odo was forced to admit to Elim Garak that, despite his disgust at the Founders' behavior, he still wanted to return home. He accompanied Garak in an attempt to contact Enabran Tain. He became a prisoner of Tain, who was plotting, along with the Romulans, the extermination of the Founders. The plot failed, and Odo was aided in his escape by a Founder who was posing as a Romulan on Tain's ship, although he still rejected the offer to return home. This resulted in the disastrous Battle of the Omarion Nebula, in which both the Romulan Tal Shiar and Cardassian Obsidian Order were decimated. (DS9: "Improbable Cause", "The Die is Cast")
In late 2371, Odo was forced to kill a Changeling posing as Ambassador Krajensky, who had tried to provoke a war between the Federation and the Tzenkethi. He became the first Changeling ever to harm another. (DS9: "The Adversary")
Odo, along with Rom, Quark and Nog, was transported back in time to 1947 (although none of the Ferengi knew about Odo's presence, he having sneaked onto the shuttle to catch Quark smuggling). This became known in history as the Roswell Incident. They eventually escaped and returned to their own time. (DS9: "Little Green Men")
In 2372, Odo accompanied Sisko on a trip to Earth to advise Starfleet on the Changeling threat. Odo was able to show them how easy it would be infiltrate Starfleet, and subsequently helped free Sisko from a prison after Sisko's old mentor, Admiral Leyton, was revealed to be staging a military coup. (DS9: "Homefront", "Paradise Lost") While there, he was secretly infected with a morphogenic virus by the rogue organization Section 31, in the belief that he would eventually link with others of his kind, transferring the disease and ultimately eliminating his entire species. (DS9: "Extreme Measures")
He protected Shakaar Edon, the head of the Bajoran government, on his visit to the station, even though he was jealous of him because of his relationship with Kira. When Worf's brother, Kurn, arrived on the station after being dishonored by the Klingon High Council due to Worf's siding with the Federation in the Klingon attempt to conquer Cardassia, he gave him a job of security officer, although this ended when Kurn made constant attempts to die.
Later that year, Odo became desperately ill, not as a result of the virus, but because he had been poisoned by his own people in order to force him to return to them for treatment. There, he was judged by the Great Link and forced into his humanoid form permanently, unable to change shape, as punishment for harming another Changeling. While Odo was locked into a humanoid form, it hinted that he was essentially still a Changeling. Because, as Dr. Bashir would later point out, Odo's brain still contained morphogenic components. The other shapeshifters may have just used their greater collective ability while linked with Odo to force him to alter his form into that of a humanoid; guiding the specific elements of his transformation such as human physical makeup based on their expert knowledge of humans. While joined While part of the Link, he unwittingly infected his entire race with Section 31's bioweapon. (DS9: "Broken Link", "Extreme Measures")
Life as a solid
Permanently locked into his solid state, Odo became extremely depressed. He found some comfort in the new sensations of eating and drinking, but this gave him little solace. Odo's frustration was exacerbated when Captain Sisko decided to bring him on an undercover mission to expose a Changeling infiltrator in the Klingon Empire. If he had been a Changeling, Odo could have simply changed into Chancellor Gowron's pet targ. Instead he, Sisko, O'Brien and Worf disguised themselves as recipients for the Order of the Bat'leth and attempted to expose Gowron as a Changeling via polaron radiation.
Odo proved to be a less than intimidating Klingon, but the mission went as planned until someone recognized their true faces. The Starfleet officers were exposed and nearly executed, but General Martok helped them escape to complete their mission in the name of the Empire. Worf almost killed Gowron in honorable combat, but by this time, Odo had deduced that Martok was the true Changeling and his information about the infiltrator had been deliberately false to provoke further unrest between the Federation and the Klingons - weakening them and paving the way for a Dominion invasion of the Alpha Quadrant. The Martok Changeling was then killed by a barrage of disrupter fire. The mission was ultimately a success. Before undoing Odo's Klingon alterations, Bashir mentioned that he could surgically alter Odo's face to realistically resemble any humanoid; Odo declined the offer as he preferred his face the way it was. (DS9: "Apocalypse Rising")
It was during Odo's time as a solid that the USS Defiant, through the treachery of an undercover Klingon named Arne Darvin, was sent back in time to the year 2268. The ship found itself near space station K-7 at a crucial moment when Darvin had been exposed as a spy and subsequently disowned by his people. Odo helped search for an explosive tribble to prevent Darvin from killing James T. Kirk, and even acquired one as a pet. He found Worf's recounting of the Klingons' "war" against the tribbles rather amusing, finding it hard to believe that a cute ball of fur was a "mortal enemy" of the Klingon Empire. (DS9: "Trials and Tribble-ations")
Apparently, the Founders' attempt to force Odo to remain a solid took some time, as a plasma storm later reacted with leftover morphogenic enzymes and caused his mind to telepathically reach out to link with other Changelings. At the time, he was returning from a conference with Sisko, Garak and Dax, and the four of them were trapped in a dream-like but utterly realistic recreation of the Cardassian Occupation based on Odo's memories. The people in the dream believed them to be a group of Bajoran terrorists who had been executed during the Occupation, but instead of Odo, his predecessor Thrax was in charge. Odo did not realize (or did not want to admit to himself) that Thrax's actions in the dream were in fact a recreation of his own, and their personae there were a group of innocent Bajorans who had been executed because Odo sided with "justice" rather than his sense of right and wrong. The experience, a product of Odo's guilt, forced him to admit the truth to himself and others. (DS9: "Things Past")
In 2373, Quark found an infant Changeling among some salvage he had purchased, selling it to Odo. It was very sick, and, although Odo and Dr. Mora's attempts to teach it to change form as Dr. Mora had done with Odo did result in them making it form a face to look at Odo (along with various other shapes seemingly at a much faster rate than Odo had when in Mora's care), its morphogenic matrix began to destabilize. As it died in Odo's hands, it linked with Odo and restored his morphogenic matrix, allowing him to change form once again. This was done as a means of thanking its mentor for all that he had tried to do. As Doctor Mora departed the station, he encouraged Odo to think of his restored abilities as a gift the changeling wanted him to have, and Odo, in return, told Mora that he now had a better understanding of what Mora had done for him all those years ago. (DS9: "The Begotten")
The Dominion War
He joined the ruling council at the invitation of Weyoun. After the Female Changeling arrived on the station, his loyalties were in question. The Female Changeling realized that the reason Odo remained with the solids was his love for Kira. She linked with Odo, hoping to manipulate him. While Kira led a resistance cell, Odo did nothing to help. Rom was arrested, but Odo again did nothing, stating that he was at peace after his linking. Kira was later put into the brig and when the Female Changeling explained her plans for the solids, including the execution of Kira, Odo's eyes were opened. During the battle to retake Deep Space 9, Kira and Rom escaped with Odo's help. He and his security forces attacked the station's guards, allowing Kira and Rom to disable the station's weapons system, helping the Defiant retake the station. (DS9: "A Time to Stand", "Behind the Lines", "Favor the Bold", "Sacrifice of Angels")
In 2375, he tried to help Weyoun 6 defect to the Federation, as Weyoun 6 believed that the Dominion War was a mistake, but his programming meant that he still saw the Founders as gods; contacting Odo was as close to a compromise as he could come. Unfortunately, due to the attack of Weyoun 7 and four Jem'Hadar ships, the attempt failed and ended with Weyoun 6's death, the Vorta triggering a termination implant in his brain that killed him in a matter of minutes. At this time, Weyoun also revealed that the Founders were all dying of a strange disease, and Odo was the only one who seemed unaffected by the disease. (DS9: "Treachery, Faith and the Great River")
Some time after this, it was revealed that Odo was the original source of the morphogenic virus that was killing the Founders, having been infected by Section 31 during his brief visit to Earth (DS9: "Homefront", "Paradise Lost") in an attempt by Section 31 to end the threat of the Founders by committing genocide. Odo was beginning to die of the disease himself, but fortunately, after tricking Section 31 agent Luther Sloan into coming to DS9, Bashir was able to discover a cure for the virus, although it necessitated him and O'Brien each using a neural interface to enter Sloan's dying mind when the agent tried to kill himself rather than reveal the cure. (DS9: "Extreme Measures")
Odo was instrumental in ending the war with the Dominion. He and Colonel Kira joined Damar's resistance group, providing valuable help in his fight against the Dominion. When the Female Changeling refused to order the Jem'Hadar and Breen forces to stand down, Odo linked with her, curing her of the virus and convincing her that she was wrong about solids and to stand trial after ending the war. In exchange, Odo agreed to return to the Great Link permanently to help build a new Dominion, and to cure his people. Unfortunately, this meant the end of his relationship with Kira. He was accompanied on his return to the Link by Kira. As he merged into the link, he changed into a tuxedo, which Kira liked him in. (DS9: "What You Leave Behind")
Odo had a deep sense of justice, which he valued above all other things. As he told Sisko at one point, "Laws change depending on who's making them, but justice is justice." (DS9: "A Man Alone") Because of this, he enjoyed "thumbing his nose" at authority and going by his rules rather than those of Starfleet. (DS9: "The Search, Part I") He once speculated that his belief in justice was an innate part of his racial makeup, and thus a link to his lost people. (DS9: "Necessary Evil") When his people revealed themselves to be the Founders of the Dominion, they claimed that what they desired was order, not justice. (DS9: "The Search, Part II")
His service during the Occupation changed his attitudes about justice significantly. When he began working for Gul Dukat, he believed he was on neither the Bajoran nor Cardassian side, an impartial investigator whose only goal was to find the truth. Experience during the occupation and being forced to choose sides when the truth would not lead to justice caused him to realize that, contrary to the Human axiom, justice is not blind. (DS9: "Necessary Evil")
As late as 2369, Odo had never "coupled", claiming he chose not to do so. He saw too many compromises involved in humanoid relationships and failed to understand the humanoid obsession with coupling. (DS9: "A Man Alone") Odo also believed in punctuality. His daily patrols of the Promenade were so routine that shopkeepers could set their watch to him. (DS9: "Broken Link")
Shapeshifting nature and ability
Odo did not have the benefit of connection with the Great Link while he matured, and as a result he was relatively unskilled in the use of his shapeshifting abilities when compared to most other Changelings. Unlike Odo, other Changelings such as the Female Changeling, showed little difficulty in mimicking the faces of Kira Nerys and others. (DS9: "Heart of Stone", "Paradise Lost")
Nonetheless, Odo was able to improve his abilities with time and practice. By shapeshifting into an object, not only was he able to create a visual representation of the object, he was able to duplicate the object to such degree that if you scanned him with a tricorder while he was in the shape of a bird, the tricorder would detect a bird. (DS9: "Paradise Lost")
Odo did not have a sense of smell, or a sense of taste either, which is part of the reason he disliked eating; he noted once that he had actually attempted to eat shortly after he first mastered the ability to assume a humanoid form, but commented that the lack of a digestive system made the whole process very messy without elaborating further. (DS9: "If Wishes Were Horses", "Meridian", "Improbable Cause") When the situation was appropriate, Odo was able to use his shapeshifting ability to create a visage of a table setting with a meal which he could "consume," and in doing so be a part of the dining experience. (DS9: "The Way of the Warrior")
Odo did not wear real clothes, instead creating his uniform from his body. Despite his difficulties imitating certain humanoid features, he was skilled enough as a shapeshifter to imitate some technological devices well enough for them to be functional, including his combadge on his uniform. But on at least one occasion Odo elected to wear a "real" combadge. (DS9: "Invasive Procedures")
Odo could not hold a form permanently, and had to regenerate on a regular basis, generally every 16 hours. During this time he returned to his natural state for a period of several hours. Nevertheless, in 2369, while trapped in a turbolift for several hours, Odo showed signs of distress when approaching the 15th hour mark since the time of his last regeneration; physical changes in his appearance were already beginning to show. (DS9: "The Forsaken") Several years later, while bunk mates with Quark during a mission on the Defiant, Odo appeared fine physically, even if highly agitated, when he interrupted Quark's attempts to engage in conversation by explaining that he had been holding his shape for a full 16 hours. (DS9: "The Search, Part I") In one case, Garak tortured Odo by preventing him from regenerating, using an Obsidian Order device that prevented Changelings from changing form. The inability to regenerate appeared to cause Odo great distress and pain, as well as causing his physical appearance to begin to fall apart. (DS9: "The Die is Cast")
Odo employed a number of tactics in his attempts to integrate with solids; for instance, he would often sit for quiet drinks with friends, and would create the illusion of drinking by forming part of his body into a cup of coffee and then drinking himself. (DS9: "The Way of the Warrior")
Thanks to the instruction of his people, Odo began to take a great interest in his abilities as a shapeshifter, and to explore the various forms and sensations he could experience while in his liquid state. He outfitted his personal quarters to this end. (DS9: "The Search, Part II", "The Abandoned")
When he was used as a host for the memories of Curzon Dax during Jadzia Dax's zhian'tara, after Curzon left his body, he admitted to Dax that he had found Curzon's memories of various human activities such as eating, drinking, and playing tongo quite enjoyable, to the extent that he was amazed that Curzon had ever been able to get any work done. (DS9: "Facets") During his time as a solid, Odo learned to appreciate the simpler things in life. When Captain Sisko found Odo in Quark's, Sisko was surprised to find the constable was not on duty for once; he was instead studying a glass of sparkling wine. Odo observed how soothing the sound of the bubbles was. Although he had found ingestion a disgusting process at first, Odo told Sisko he had come to enjoy it. (DS9: "Apocalypse Rising")
Other aspects of monoform life proved less than comforting. In one embarrassing folly, Odo instinctively attempted to turn into a vorian pterodactyl while chasing a criminal on the promenade, but instead fell and injured himself. Additionally, he suffered from poor posture because he carried himself too rigidly for a normal humanoid. (DS9: "The Ascent", "The Begotten")
Odo also had a penchant for the Earth sport of kayaking. He and O'Brien occasionally used a kayaking holoprogram, which O'Brien brought with him from the USS Enterprise-D. Odo found the experience "quite enjoyable," although he refrained from singing sea shanties while they paddled. (DS9: "Heart of Stone")
Odo found humanoid death rituals fascinating, particularly the Ferengi tradition of vacuum desiccation. When Quark was selling discs of the recently deceased Ferengi entrepreneur Plegg, Odo sarcastically informed Quark of his interest in the subject and offered to buy a disc, much to Quark's surprise. It turned out that Plegg was very much alive and that Quark had been cheated. Plegg found this very amusing, although Quark and Odo did not. (DS9: "The Alternate")
Odo found his position as umpire for the Niners' game against the Logicians fascinating. He took his duties very seriously, to the point that he threw Benjamin Sisko out of the game. Later, he also threw out the Vulcan captain Solok for simply tapping him. (DS9: "Take Me Out to the Holosuite")
Although Odo was ostensibly an "orphan" from his beginnings of life in the Alpha Quadrant, Dr. Mora liked to think of himself as Odo's father and referred to himself as such on several occasions. Odo resented this presumption and preferred to forget his time in Mora's laboratory, mainly due to the various shock treatments he had been subjected to before it was realized that he was a sentient being. (DS9: "The Alternate") When Mora helped Odo care for an infant changeling, the two of them bonded better, Odo realizing what Mora went through while "raising" him, and understanding how hard it must have been for Mora when he left. (DS9: "The Begotten")
In a manner of speaking, all Changelings, and particularly the Great Link, were his family. He felt an irreconcilable estrangement from the Link when he discovered their hatred of the solids and that they were the leaders of the ruthless Dominion. (DS9: "The Search, Part I", "The Search, Part II")
From the time Quark opened his bar on DS9, he and Odo were constant antagonists. Regardless, they maintained a mutual respect for one another, and Quark once observed that as Odo's worst enemy, he was the closest thing the shapeshifter had to a friend. (DS9: "A Man Alone") Odo always kept a vigilant eye on Quark's illicit activities, but in many cases, he was able to use Quark's underground contacts to infiltrate criminal organizations to which he would not otherwise have access. (DS9: "Indiscretion")
The two often had idle conversations at Quark's Bar while Odo was on duty and Quark was working. They maintained their rivalry, yet were fond of each other's company and their regular exchange of insults. For example, Odo simply "hrmphed" when Quark, in his momentary capacity as Grand Nagus of the Ferengi Alliance, told him to kiss the Nagal staff, yet he was confounded by a sudden burst of cooperation in 2370, which was actually Quark's interpretation of the 76th Rule of Acquisition: "Every once in a while, declare peace. It confuses the hell out of your enemies". (DS9: "The Nagus", "The Homecoming") During a temporary crisis in which a group of non-corporeal beings caused people's wishes to come true, Odo amusingly wished Quark into a holding cell without thinking about it. (DS9: "If Wishes Were Horses")
More than anyone else, Quark knew about Odo's secret feelings for Kira and confronted him about them several times. It was Quark who told Odo that Odo was in love with Kira, breaking through the defenses Odo had carefully erected to keep his personal life private. Odo did not want Quark's sympathy, but when Kira officially began dating First Minister Shakaar, it was Quark who came to his quarters to check on him. There, he set Odo straight, although with the usual facade; Quark ran a regular betting pool on how long it would take Odo to catch a perpetrator, and he claimed his profits would suffer if Odo did not rectify things and get back to work.
By choice, Odo's quarters were directly above Quark's, and at times he took perverse (albeit secret) pleasure in annoying the Ferengi by practicing his shapeshifting skills during the night. Whether it was a Takaran wildebeest or a Rafalian mouse, Odo was able to annoy Quark whenever he felt like it. Once he set aside his feelings for Kira and got on with his life, Odo conveniently had his floor reinforced. As this would also soundproof the floor, Quark saw that his advice had helped and thanked Odo. (DS9: "Crossfire")
In a mental recreation of Terok Nor during the occupation, Odo (seen as a Bajoran) had to do subsidiary work at Quark's Bar which he felt quite humilating. He asked Captain Sisko "How much damage would it do to the timeline if Quark were to suffer a mysterious... accident?" (DS9: "Things Past")
When Odo left DS9, he attempted to do so without anyone noticing, but Quark caught up with him in the airlock. Odo claimed to have nothing to say to the Ferengi, but while he did not say so, it was clear Odo would miss his long-time adversary. When Kira tried to apologize for Odo's coldness, Quark said "That man loves me - you can see it written on his back". He later admitted to Kira before entering the Great Link that he would miss everyone aboard DS9, even Quark. (DS9: "What You Leave Behind")
Worf and Odo both enjoyed their privacy, and they shared a dislike of unexpected visitors. Although the two of them did not become close friends (as was the case with most of Odo's friendships), Worf and Odo respected and understood each other, as in many ways they had similar personalities.
The two of them clashed while Worf was attempting to acclimate himself to life aboard DS9. Worf observed that Quark was conducting smuggling activities and informed Odo about it only to find that Odo already knew of the transactions. Unknown to Worf, Odo was conducting an undercover operation and planned to use Quark's clandestine connections to infiltrate a large smuggling ring. When Worf placed Quark and Quark's contact under arrest, he discovered that the container in which the payment for the illicit goods were located was actually Odo in disguise. (DS9: "Hippocratic Oath")
Once the two learned each others' ways, they found they could relate to one another far more than they realized. Odo offered Worf advice on how to keep people from simply "dropping by" his quarters. (DS9: "Crossfire")
Miles O'Brien and Odo had a good working relationship. Odo volunteered to represent O'Brien when he was tried in a Cardassian court, successfully proving O'Brien's innocence despite the Cardassian legal structure regarding the trial as a mere formality for a pre-determined sentence. This trial gave Odo the opportunity to get to know O'Brien better and develop an admiration for his strong sense of duty when he proclaimed that he had always tried to be somebody his children could be proud of. A couple of years later, he allowed the O'Briens to return the temporally-displaced Molly O'Brien to Golana, even though they broke her out of a holding cell. He joked that he was actually disappointed as he expected O'Brien to succeed in breaking someone out of the station without being discovered. (DS9: "Tribunal", "Time's Orphan")
O'Brien and Odo went kayaking in a holosuite several times; an activity Odo found "quite enjoyable". (DS9: "Heart of Stone") Odo (or the impostor changeling trying to pass as him) tried to use knowledge of details from their most trip to prove he was the real Odo (DS9: "The Adversary")
Garak and Odo were forced to work together during the events leading up to the joint Tal Shiar-Obsidian Order strike on the Founders' homeworld. What began as a decidedly unwilling partnership, evolved into a mutual respect as Garak began to understand that, unlike his other erstwhile sparring partner Doctor Julian Bashir, Odo truly understood who Garak was. Strangely, Garak's attempt to torture Odo while trapped on the Tal Shiar ship created a mutual understanding and a peculiar bond between them. Garak recognized that he no longer had the will to torture those he was close to, and Odo empathized with Garak's willingness to do anything to return to his own people. They later had many quiet "drinks" together. (DS9: "Improbable Cause", "The Die is Cast", "The Way of the Warrior")
Although Odo noted that he didn't think he would like Benjamin Sisko when he first met him, the two formed a keen respect for each other over the years. When Sisko was promoted to Captain, Odo noted that, while he didn't personally see the relevance of such titles, he could think of nobody who deserved this ritual more than Sisko. Sisko reciprocated this admiration more than once. When Odo's life was at stake following his capture by the Obsidian Order and later his illness, Sisko took the Defiant into Dominion territory to save Odo, despite the risks of conflict with the Dominion. Odo also accompanied Sisko back to Earth when they received news that the Changelings had reached Earth. He helped him develop means of detecting Changelings on the planet. On another occasion he helped Sisko, who was falsely accused of being a Changeling by Admiral Leyton, escape. (DS9: "Emissary", "The Adversary", "The Die is Cast", "Paradise Lost", "Broken Link")
While on a routine mission in the Alpha Quadrant, Odo and Chief O'Brien happened upon another Changeling named Laas. Odo was fascinated, as Laas too was one of the hundred infant Changelings the Founders had sent out to learn about other civilizations. The two of them bonded quickly, and Odo was able to tell that Laas' intentions were good despite the chief's concerns.
Laas did not integrate well when they returned to the station. He openly stated his dislike of "solids," much to Odo's chagrin. Laas believed Odo had been brainwashed into acting and thinking like a solid, making excessive and disruptive use of his own shapeshifting abilities to prove his point. Ultimately, Laas left in search of other Changelings in order to form a second Great Link. (DS9: "Chimera")
Over the years, Odo began to fall in love with Kira Nerys. He kept this a secret from her, and stood by as she entered into and ended other romantic relationships, including the death of Vedek Bareil Antos; after Bareil's death, Kira took up a relationship with Shakaar, the head of the Bajoran government. Although she eventually learned his true feelings after an encounter with an alternate future version of him, Kira and Odo were left reluctant to pursue a relationship at the time, due in no small part to the future Odo having erased over eight thousand people from existence simply to prevent Kira's death in his original timeline and give his younger self another chance with her. Eventually, with the help of Vic Fontaine, he finally revealed his feelings for her in 2374, Kira reciprocating his feelings. Despite this, Odo left Deep Space 9 at the end of the Dominion War to heal the Great Link of a virus that was killing the Changelings and showing them positive aspects of the solids. (DS9: "Children of Time", "His Way", "What You Leave Behind")
Ambassador Lwaxana Troi was infatuated with Odo from the moment she saw him. As she put it, "I've never been with a Changeling before!" Odo found Lwaxana's advances annoying and even complained to Commander Sisko that Ambassador Troi wouldn't leave him alone. An accident later trapped the two of them together in a turbolift shortly before Odo was set to revert to his gelatinous state. Over the course of several hours, the two of them finally began to understand each other.
They were stuck in the turbolift so long that Odo could barely hold his shape and was literally "melting." Lwaxana offered to carry Odo in her dress, but he was too proud as no one had ever seen him in his liquid form. Finally, she removed her wig and admitted that no one had ever seen her in her natural state either. Odo felt more at ease after this revelation and allowed Lwaxana to carry him. (DS9: "The Forsaken")
During Ambassador Troi's next visit to DS9, her persistent feelings for Odo combined with her case of zanthi fever to cause strange love triangles to form among the occupants of DS9, such as Jake Sisko and Doctor Bashir both becoming fixated with Kira. (DS9: "Fascination")
Lwaxana's final visit with Odo was under duress, as her Tavnian husband was intent on taking her unborn child when it was born. In Tavnian culture, boys and girls were raised under strict gender separation, something Lwaxana's husband had initially promised would not be the case for their child (he later declared his intention to take her male child as soon as it was born, disregarding his previous assurances to her). Odo protected her long enough to keep her husband at bay and ultimately married her in Tavnian tradition in order to end the biological father's legal claim to their offspring under Tavnian law (which specified the mother's husband as the legal guardian for male children). This required a public profession of his love for her, which although forced (and not of a genuinely romantic nature), came across as incredibly candid. (DS9: "The Muse")
An Idanian woman named Arissa once fell for Odo while he was protecting her from the group who were trying to kill her, the two even spending the night together (a first for Odo, outside of a single pseudo-sexual encounter during his brief time on the Founder homeworld). Later, he found out that she was an agent sent into deep cover to infiltrate the Orion Syndicate. She was married and, due to her mind having been altered to escape telepathic examination, she did not know this while she was undercover. As she departed, she assured Odo that she had genuinely cared for him in their time together. (DS9: "A Simple Investigation")
During the Dominion's occupation of Deep Space Nine, Odo became involved with the Female Changeling. Initially, his only intent was to learn more about his own people and perhaps influence her towards a peaceful resolution of the current conflict. However, she was able to manipulate him and his desire for control over his own emotions regarding Kira. Eventually she was able to almost completely turn Odo away from his former friends and allies, but the revelation that she intended "to break" the Alpha Quadrant peoples of their desire for freedom shocked him into reconsidering his new "perspective". He effectively ended their personal relationship by siding once again with the Federation against the Dominion. (DS9: "Sacrifice of Angels") Later, at the end of the war, he was able to save her life from the morphogenic virus and convince her to give the stand-down order to the remaining Dominion forces by promising to return to the Great Link with the cure. (DS9: "What You Leave Behind")
2373: The dying act of an infant Changeling is to make him a Changeling once more.
2375: Leaves DS9 to rejoin his people in the Great Link
Alternate realities and timelines
In an alternate timeline in which Harry Kim was never assigned to the USS Voyager, Odo arrested Tom Paris in 2371 after he attacked Quark in his bar. Consequently, Tom was still sitting in a holding cell on DS9 when Voyager was thrown into the Delta Quadrant. (VOY: "Non Sequitur")
In an alternate timeline in which the Defiant was sent back in time to the 22nd century, Odo was the only member of the crew (besides Dax) who lived to see the Defiant arriving in the 24th century. In two hundred years, he had grown more proficient in shapeshifting and was able to assume a more humanoid face. In this time, he admitted his feelings for Kira, and subsequently linked with his younger self. He sabotaged the Defiant and caused it to avoid crashing on Gaia, wishing to give his younger self and Kira a second chance at love. By doing so, the inhabitants of Gaia ceased to exist. (DS9: "Children of Time")
Odo was holographically duplicated at least once.
- Luther Sloan recreated the entire station, and staff, of Deep Space 9 in 2374 as part of his investigation into Julian Bashir, including Odo. (DS9: "Inquisition")
"You can tell a man's intentions by the way he walks."
"They were an ecological menace, a plague to be wiped out."
"Wiped out? What are you saying?"
"Hundreds of warriors were sent to track them down throughout the galaxy. An armada obliterated the tribble homeworld. By the end of the 23rd century, they had been eradicated."
"Oh, another glorious chapter in Klingon history. Tell me, do they still sing songs of the Great Tribble Hunt?"
"Come on, Quark, move it along. You should be in the emergency shelter by now."
"I'm not going to any emergency shelter. This is my bar. And I'm going to defend it."
"Really? And how do you plan to do that?"
"You're going to hit them with a box?"
"No, this is my disruptor pistol. The one I used to carry in the old days, when I was serving on that Ferengi freighter."
"I thought you were the ship's cook."
"That's right, and every member of that crew thought he was a food critic. If the Klingons try to get through these doors, I'll be ready for them."
(reads note in the empty box) " 'Dear Quark, Used parts from your disruptor to fix the replicators. Will return them soon. Rom.' "
"I will kill him!"
"You are a thief!"
"All right, let's try again. Close your eyes, take a deep breath... clear your mind of anything in it... if there's anything there..."
"Someone's extracted all the latinum! There's nothing here but worthless gold!"
"And it's all yours."
"It's just Quark's luck that you would be assigned quarters right above his."
"Luck had nothing to do with it."
"But don't worry - I plan to investigate the Klingons, the Bajorans, Quark, the visiting Terrelians..."
"You think Quark had something to do with this?"
"I always investigate Quark."
"I have a friend at Starfleet Intelligence. And she has a friend who has a cousin who's married to the assistant of one of the members of the Federation Medical Council."
"And according to my friend, her friend heard something from his cousin that his wife heard from this council member that I thought you might find interesting."
"Doctor Wade is not going to win the Carrington."
- Odo was played by Rene Auberjonois throughout the entire run of Star Trek: Deep Space Nine.
- Odo has also been played by Salome Jens (when he took the form of the Female Changeling in "Tacking Into the Wind" to infiltrate a Jem'Hadar ship), several unnamed animals (including rats, birds, and a German Shepherd), and various inanimate objects.
- As Michael Piller explains, the origins of the character are to be found in the fact that "we needed a character who represented the traditions of Spock and Data, the outsider who looks in at humanity." (New Frontiers: The Story of Deep Space Nine, DS9 Season 2 DVD, Special Features)
- The original 1992 Writers' Bible for Star Trek: Deep Space Nine gave this biography for Odo:
- Odo, an alien male, middle-aged curmudgeon, and a shape-shifter. In his natural state he is a gelatinous liquid. He was Bajoran law enforcement officer on the space station under the Cardassians. Starfleet decides to have him continue in that role, since he's extremely savvy about the Promenade and all who frequent it. His back story is: 50 years ago, with no memory of his past, he was found alone in a mysterious space craft that appeared in the Denarias asteroid belt. He was found by the Bajoran and lived amongst them. At first he was sort of an Elephant Man, a source of curiosity and humor as he turned himself into a chair or pencil. Finally he realized he would have to take the form of a humanoid to assimilate and function in their environment. He does it, but resents it. As a result, Odo performs a uniquely important role in the ensemble: he is a character who explores and comments on human values. Because he is forced to pass as one of us, his point of view usually comes with a cynical and critical edge. But he can't quite get it right, this humanoid shape, though he continues to try. So he looks a little unfinished in a way. He's been working on it a long time. Someone might ask him: Why dont you take the form of a younger man. His answer: I would if I could. He has the adopted child syndrome, searching for his own personal identity. Although he doesn't know anything about his species, he is certain that justice is an integral part of their being, because the necessity for it runs through every fiber of his body -- a racial memory. Thats why he became a law man. He has a couple of Bajoran deputies; he doesnt allow weapons on the Promenade, and once every day he must return to his gelatinous form.
- According to Rene Auberjonois, "Constable Odo was envisioned originally as a kind of young John Wayne sheriff-in-town." Similarly Ira Steven Behr states, "I was told six months before the series began that Odo was going to be a Clint Eastwood type, and when we started creating the first couple of episodes, we sent writers off to write Clint Eastwood. And then I was told Rene Auberjonois. And I said, 'Clint Eastwood, Rene Auberjonois? Clint Eastwood, Rene Auberjonois? Does not compute.' And then I saw what he brought to the role, and I had to call up a whole bunch of writers and say 'Guys, I apologize, but this is better than we even imagined.'" (Crew Dossier: Odo, DS9 Season 3 DVD special features)
- Although Rene Auberjonois himself was initially unsure as to whether or not he could play the role, his daughter had no such doubts; "When the script was first sent to me and I read the description of the character, my daughter said to me, 'Oh dad, yeah, this is yours, you're gonna get this.' My kids were completely confident that this part was for me, which, considering the nature of the character, I don't know if I should take that as a compliment or not." (Hidden File 04, DS9 Season 1 DVD special features)
- The name Odo is shared with a central character in Ursula Le Guin's 1974 novel The Dispossessed. The character, ironically and in contrast to the Odo of Deep Space Nine, is an anarchist. Michael Piller originally called the character "Otto", but Rick Berman changed it to "Odo". (New Frontiers: The Story of Deep Space Nine, DS9 Season 2 DVD special features)
- Odo's relationship with Quark is a clear homage to the classic 1942 Michael Curtiz film Casablanca, with Odo in Claude Rains' role of Captain Louis Renault and Quark as Humphrey Bogart's Rick Blaine, although the garrulous Renault and taciturn Blaine are somewhat the opposite in personality to their counterparts. At one point Quark notes, "Everybody comes to Quark's," a nod to the title of the play on which Casablanca is based (Everybody Comes to Rick's by Murray Burnett and Joan Alison), while in "The Ascent", he asks "Do you think this is the beginning of a beautiful friendship?", a twist on the film's closing line.
- Several scripts refer to Odo's superior strength, such as "Vortex"  and Odo has no sense of smell. (DS9: "If Wishes Were Horses")
- Odo 1, a combat training holoprogram
- Odo's bucket
- Odo One, a program used to drive away the Saltah'na energy spheres
In the DS9 Relaunch novels, Odo sends a Jem'Hadar ambassador to the Alpha Quadrant to foster understanding in the Dominion of other cultures. He soon returns to DS9 and reunites with Kira.
Odo later learns that the Hundred were initially sent out to find the Progenitor- the first changeling and the key to solving their declining population as changelings cannot reproduce (Odo and the other Hundred were not 'infants', but merely changelings that had never been part of the Great Link)-, but the discovery of the Progenitor's death causes the changelings to disperse across the quadrant; as of 2382, Odo has only rediscovered approximately thirty changelings- including himself and Laas- to form a new Link.
According to the Star Trek: Terok Nor novel Night of the Wolves, Odo was found in a spherical module in the Denorios Belt by the Cardassian vessel Kevalu, which was under the command of Dalin Malyn Ocett, in 2345.
In the Star Trek: Typhon Pact novel Raise the Dawn, Odo returns to the Alpha Quadrant to help Sisko investigate reports that the Typhon Pact- an alliance of the Federation's enemies- have stolen Jem'Hadar techology to perfect their own quantum slipstream drive, only to be trapped in the Alpha Quadrant when the wormhole is seemingly destroyed thanks to Kira's attempt to stop a Typhon Pact ship using it again. Sisko offers Odo a place on his new ship, the Robinson, but the novel ends with Odo deciding to remain on Bajor for a time to think about what he will do next.