Miles O ' Brien Miles Edward O ' Brien was a 24th century Human Starfleet noncommissioned officer who , following his service during the Federation - Cardassian War , served as transporter chief on board the for several years before being promoted to Chief of Operations aboard starbase Deep Space 9 . After the Dominion War he accepted a teaching position at Starfleet Academy on Earth . Early life . Miles O ' Brien was born in Ireland , Earth , in September 2328 . ( ) O ' Brien claimed he could trace his ancestry back to the 11th century Irish king Brian Boru ( whom he occasionally played in a holosuite program ) . Another notable O ' Brien ancestor was Sean Aloysius O ' Brien . ( ) O ' Brien was proud of the fact that he was raised on real food as his mother believed that replicated food was less nutritious . When preparing meals for her family , his mother would handle and cook meat . ( ) O ' Brien had two brothers . His mother passed away in 2368 and his father , Michael , remarried a year later , though Miles never met his new stepmother . ( ) His relationship with his father had been a somewhat rocky one during Miles ' adolescence ; Michael had pushed Miles to pursue his music career , making him practice at least once a day , and was somewhat upset by his son ' s enlistment in Starfleet . When Miles was seventeen years old , his father sent a recording of his work to the Aldeberan Music Academy . O ' Brien declined the offer of admission to the music Academy and enrolled in Starfleet – against his father ' s wishes . The two later reconciled their differences and O ' Brien ' s father was eventually extremely proud of his son and his accomplishments . ( ) As a child , O ' Brien had a morbid fear of spider s . Following a mission on Zayra IV where O ' Brien was forced to make a critical repair in a Jefferies tube containing Talarian hook spider s , he found that his fear had lessened , and he later kept a Lycosa tarantula , named Christina , as a pet aboard the " Enterprise " - D . ( ) Starfleet career . In 2345 , at the age of 17 , O ' Brien joined Starfleet as an enlisted crewman . As of stardate 49648 . 0 , O ' Brien had served aboard a half dozen starships , participated in 235 separate combat engagements , and been decorated by Starfleet on fifteen occasions . Because of his impressive military record O ' Brien was recognized by a formal Starfleet inquiry as an expert in starship combat . O ' Brien ' s career was so well respected that Captain Keogh of the considered the chief ' s experiences an asset before launching a rescue mission for Commander Benjamin Sisko . O ' Brien was even styled " the hero of Setlik III " due to his actions in an engagement with Cardassian forces on that planet , a title he seemed to tolerate rather than enjoy . During a salvage mission to Empok Nor , Elim Garak challenged O ' Brien to a game of Kotra , saying he would love to play against the " Hero of Setlik III . " ( ) The USS " Rutledge " . One of his first assignments was aboard the under the command of Benjamin Maxwell , where he served as junior tactical officer during the Cardassian War . A year later , O ' Brien was present at the aftermath of the Setlik III massacre , where his technical skill was useful in repairing a field transporter , allowing himself and thirteen other Starfleet personnel to escape a Cardassian patrol . This earned him a promotion to primary tactical officer . O ' Brien also served as part of a squad to aid the survivors of the massacre , as Cardassians were still patrolling the settlement ; he helped a group of women and children but was ambushed by two Cardassians . He was able to incapacitate one of them , but in fighting with the other one he accidentally killed his assailant when a phaser passed to him was set to maximum . Until then , O ' Brien had never killed anything or anyone ( he was even worried about swatting mosquito es as a child ) and the incident left him with a deep - seated resentment towards Cardassians , bordering on outright racism on occasion . He often referred to them by the derogatory term " Cardie s " . ( ) Many years later , he remarked to Glinn Daro that it was not Cardassians that he hated , but rather the person he became because of them . ( ) The USS " Enterprise " - D . O ' Brien transferred to the USS " Enterprise " - D in 2364 with the rank of chief petty officer , under the command of Captain Jean - Luc Picard . During the Farpoint Mission he was assigned as relief flight controller . He also stood duty in the security department , but was most often seen working as transporter chief , where he was involved in , among other events , the rescue of Captain Picard from the Borg in 2367 . ( ) In 2367 , Miles was forced to confront his former commanding officer when Captain Maxwell went rogue , launching attacks on Cardassian outposts and ships in spite of a peace treaty between the Federation and Cardassia . O ' Brien ' s knowledge of transporter systems allowed him to beam aboard Maxwell ' s ship , the , while her shields were up , giving him a chance to reason with Maxwell , ultimately preventing further bloodshed . ( ) During the Klingon Civil War , O ' Brien also made use of his training as a tactical officer following Lieutenant Worf ' s resignation from Starfleet . As a result , he was heavily involved in the deployment and maintenance of the tachyon detection grid that ultimately decided the conflict . ( ) In 2368 , a quantum filament caused major damage to the " Enterprise " . Unable to communicate with the rest of the crew , O ' Brien , together with Lieutenant Commander Deanna Troi , Ensign Ro Laren , and Ensign Mandel , was trapped on the bridge , while his heavily - pregnant wife Keiko was stuck in Ten Forward . The quantum resonance of the filament caused a polarity shift in the ship ' s antimatter containment fields , leading to a progressive degeneration in the fields , threatening the ship . Ro suggested a saucer separation to save the primary hull , while sacrificing the stardrive section . O ' Brien strongly opposed this plan and stated that it would be a " pretty cold - blooded thing to do . " Eventually , thanks to his prowess in keeping the containment field stable long enough , Troi rejected Ro ' s proposal , and the antimatter containment was fully restored by Commander Riker and Lt . Commander Data shortly before Keiko delivered her baby in Ten Forward . ( ) Later that year , Miles , along with Troi and Data , was taken over by an alien lifeform which forced them to take hostages to use as a bargaining chip in negotiating with Picard . Among the prisoners were Molly and Keiko O ' Brien . Eventually , the lifeform left when it was discovered that the moon was actually a " penal colony " and that this was an attempt to escape . ( ) Deep Space 9 . By 2369 , O ' Brien had been serving in Starfleet for 22 years . In that year , O ' Brien left the " Enterprise " , transferring to Deep Space 9 with a promotion , assigned the role of chief of operations . His primary task during the early days of his posting was to repair the damage done during the withdrawal of the Cardassians from the station . He was instrumental in moving the station from its orbit of Bajor out to the Denorios belt , following the discovery of the Bajoran wormhole . ( ) Not long after , O ' Brien received a note on his record for violating the Prime Directive , after assisting in the escape of a Tosk , one of the first contacts from the Gamma Quadrant , disobeying direct orders from Commander Sisko . Tosk was a being raised to be the prey in a hunt by those known as the Hunters . ( ) He later found himself entangled in local Bajoran politics and folklore when visiting a remote village on the planet . Following the death of the local , O ' Brien was thrust into the role , forcing him to try and maintain the unity and strength of the inhabitants against a Dal ' Rok . ( ) In 2369 , O ' Brien ' s assistant Neela attempted to assassinate Vedek Bareil . O ' Brien discovered the plot and informed Sisko just in time to save Bareil ' s life . ( ) He assisted Kira Nerys in rescuing Li Nalas from a Cardassian labor camp , and defended the station against the Circle , a Bajoran terrorist group who wanted the Federation to leave the sector . ( ) In 2370 , O ' Brien was assisting the T ' Lani and Kellerun militaries in disarming and neutralizing their harvester weapons when a sabotage attempt exposed him to deadly nanobiogenic gel . In the resultant escape and rescue , he almost succumbed to his injuries , but was saved by Julian Bashir , an act which developed their friendship ( see Personal , below ) . Several months later , while assisting in preparations for a Parada peace conference on Parada II , O ' Brien was kidnapped and replaced with a replicant , created to disrupt the conference . The duplicate O ' Brien later died after others became aware of the threat he posed , and the real O ' Brien was recovered by DS9 personnel . ( ) Later that year , Quark tried to use Bashir and O ' Brien in a racquetball scam . He had fixed the game in O ' Brien ' s favor and with everyone betting on Bashir , intended to clean up . ( ) O ' Brien became stranded with Sisko on an Earth colony , where an energy dampening field made it impossible to communicate with the orbiting runabout to leave the planet . O ' Brien found out that it was an artificial field and was able to turn it off . ( ) Sometime around stardate 47944 , O ' Brien was arrested by Cardassian forces and put on trial for allegedly supplying weapons to the Maquis , based on , among other evidence , a falsified voiceprint . The charges were later discovered to be part of a conspiracy to discredit the Federation and give the Cardassian Union a stronger position from which to negotiate , and O ' Brien was released . ( ) In 2371 O ' Brien helped disable a self - destruct mechanism on the station left by the Cardassians . He helped rescue Sisko from the past , and also worked with a group of female Cardassians on a science project on the station . One of the scientists wanted to become romantically involved with him , but he refused . ( ) O ' Brien was killed later in 2371 , after becoming infected with delta - series radioisotopes following an accident aboard the station . This , coupled with the presence of a cloaked Romulan Warbird nearby , had the effect of shifting him forward in time by several hour s . His death occurred when he deliberately contaminated himself further in order to determine the exact cause of events he had witnessed . He was ' replaced ' by his counterpart from the timeline he visited . Thus , events that occurred to O ' Brien from this point on involved the future version , rather than the " original " . ( ) When the Klingon s attacked and invaded Deep Space 9 in early 2372 , O ' Brien defended Ops against boarding parties , suffering minor injuries in the attack . At the time of the attack , O ' Brien had been completing the retrofit of the station ' s weapons arrays . ( ) His image was accidentally used in a holo - program by Julian Bashir and Garak when a runabout he was on was destroyed by Cardassian terrorists . The computer , under direction of Michael Eddington , stored his physical image in the open holosuite program ( as the evil assassin Falcon ) while his conscious mind was stored in DS9 ' s computer core . ( ) Later that year , O ' Brien had been falsely accused of espionage , and was given the simulated memory of a 20 - year prison sentence following a visit to the planet Argratha . Upon returning to the station , O ' Brien became paranoid and emotionally distressed which caused angry outbursts . He even began experiencing hallucinations of his cellmate Ee ' char . Miles was temporarily relieved of his duties by Captain Sisko , on the recommendation of Doctor Bashir . As O ' Brien ' s condition deteriorated , he attempted suicide on at least one occasion , but was stopped by Bashir . ( ) In late 2372 , O ' Brien commented that his career had included service on half a dozen ships . Even though none of those vessels had cloaking device s , O ' Brien eventually became so used to the being cloaked that he felt vulnerable aboard uncloaked ships . He took part in the joint effort between the Federation and Jem ' Hadar to track down a group of renegade Jem ' Hadar soldiers that captured an Iconian gateway . ( ) In 2373 , O ' Brien took part in an infiltration mission to the fortified Klingon moon of Ty ' Gokor in an attempt to expose Gowron as a Changeling . For the mission , Miles had to be surgically altered to appear Klingon . ( ) O ' Brien , as part of a " Defiant " away team , discovered a crashed Jem ' Hadar ship on a planet . When a Vorta and a team of Jem ' Hadar came to retrieve the ship , a fight broke out . A crewman O ' Brien had become close to , Enrique Muniz , also died as a result of wounds he received in battle , and this affected O ' Brien deeply . ( ) While away on Bajor , Keiko became possessed by a Pah - wraith . It threatened to kill Keiko unless O ' Brien helped it to blow up the wormhole . He tricked it on the way to the wormhole and used the very energy beam it intended to kill the Prophets with to kill it instead , saving Keiko . He also went back in time to the original " Enterprise " and met Captain Kirk , helping to stop a Klingon from assassinating Kirk and changing history . ( ) On an assignment to Empok Nor to get a part necessary for the station , he and his team found two Cardassians in stasis . Upon waking , they murdered some of the team before Garak killed one of them . Garak became infected with a drug in the Cardassians ' systems and turned into an insane murderer , killing the other soldier and one of O ' Brien ' s crew before O ' Brien was able to disable him and return him to the station for treatment . ( ) Service during the Dominion War . O ' Brien was partly responsible , along with Rom and Jadzia Dax , for creating and deploying the self - replicating mine field that blocked Dominion ships from entering the Alpha Quadrant , an event which precipitated the Dominion War . Miles abandoned the station with the rest of the station ' s Starfleet complement , taking station aboard the " Defiant " , where he remained for the first three months of the war . ( ) Along with the rest of the DS9 command crew , O ' Brien was pulled from front - line duty to take a captured Jem ' Hadar vessel behind enemy lines . Despite his love of field ration s , O ' Brien bemoaned the lack of a replicator aboard the commandeered vessel . When the vessel crash - landed shortly after achieving its objective , O ' Brien tore his uniform , much to his chagrin and the amusement of his colleagues . ( ) He was part of the away team that confronted the Jem ' Hadar on a planet after both sides crashed . The Jem ' Hadar were betrayed by their Vorta and led into an ambush . The Vorta was about to run out of ketracel - white and feared the Jem ' Hadar would kill him . ( ) Following their rescue by the " Rotarran " , Miles took part in Operation Return , which successfully recaptured the station . He resumed his duties aboard the newly - retaken Deep Space 9 . Shortly thereafter , he played a ceremonial role in the wedding of Jadzia Dax and Worf . ( ) When the " Defiant " was captured by Jem ' Hadar forces during a scientific mission , O ' Brien was able to help Ensign Nog gain control of the ship from engineering by re - routing the bridge access codes . ( ) In mid - 2374 , O ' Brien was recruited by Starfleet Intelligence to infiltrate the Orion Syndicate arm on Farius Prime . During the mission , Miles grew friendly with Liam Bilby , a Syndicate operative . After Bilby was killed attempting to assassinate the Klingon ambassador , O ' Brien took in his cat , Chester , as a family pet , and paid money into an account for his wife . ( ) In late 2374 , Molly fell into a time portal placing her 300 years in the past . Upon being rescued , she was a teenager who had lived her life in a prehistoric era . She was unable to cope , and when returned into the portal found herself as an eight year old , where she helped guide herself back to her parents . ( ) Following the death of Jadzia Dax in late 2374 , O ' Brien took part in the " Rotarran " s successful assault on the Monac shipyards , a mission intended by Worf to get his wife into " Sto - vo - kor " . ( ) Later in 2375 , Miles disappeared on New Sydney while attempting to track down Morica Bilby , Liam ' s wife , who had disappeared from her home on the planet . O ' Brien ' s mission was unauthorized , and he received a reprimand as a result . ( ) Shortly before the final battle of the war , O ' Brien took part in the attempt to restore Vic Fontaine ' s casino . It had been taken over by Chicago gangsters . ( ) Shortly before the end of the war , O ' Brien accepted a position at Starfleet Academy as a professor of engineering . Following the Battle of Cardassia , O ' Brien departed Deep Space 9 for Earth , to take up this new role . Immediately prior to leaving , he was still considering where exactly his family would settle on Earth . His crewmates all gave suggestions : Worf was particularly insistent he look at Minsk . ( ) Personal Relationships . Family . He married Keiko Ishikawa aboard the " Enterprise " on October 24th , 2367 , and the couple had their first child , Molly , the following year . ( ) Both joined O ' Brien aboard DS9 , albeit reluctantly on Keiko ' s part , where their second child , Kirayoshi , was born in 2373 . O ' Brien had a difficult time dealing with this pregnancy , mainly as a result of the baby ' s forced ' relocation ' to Kira Nerys in late 2372 , which saw the two struggling with a mutual attraction – one which both agreed to put aside . ( ) As a ritual before going into battle , O ' Brien recorded a " goodbye " message for his family in the event of his death . Each time he did so , he believed it would be the one they would hear . Between 2367 and 2372 , he had recorded a total of eleven messages . ( ) Friends . Although an enlisted crewman with little official standing in his posts , O ' Brien has regularly shown a talent for connecting with his commanding officers ; Captain Benjamin Maxwell once described O ' Brien as the finest tactical officer he ever had , and Captain Picard noted that Transporter Room Three – O ' Brien ' s favorite room – wouldn ' t be the same without him . O ' Brien generally reciprocated this respect , noting once in a conversation with Picard when discussing his past service with Captain Maxwell that he considered himself fortunate to have served under Starfleet ' s two finest captains , and later demonstrating the same respect to his new commanding officer , Benjamin Sisko . ( ; ) Julian Bashir . Aboard Deep Space 9 , O ' Brien forged a strong friendship with Julian Bashir , the station ' s chief medical officer . Even though Dr . Bashir did take a liking in O ' Brien , that sentiment was not reciprocated at first as Miles considered him arrogant and too talkative . He was also not looking forward to calling him by his first name as he had asked him to . Mutual respect developed when the two had to work together to survive on T ' Lani III . When the two thought they were about to be killed , O ' Brien admitted it was an honor to serve under the doctor . ( ) A friendly rivalry developed between the two in racquetball , darts , and other activities . The two were frequent users of the station ' s holosuite s , usually for historical reenactments of events such as the Battle of Britain , Battle of Clontarf and even created their own programs , including an accurate depiction of the Alamo . ( " et al . " ) Their friendship grew so close that O ' Brien considered Bashir as important to him as his wife . While drinking and trying to cheer up Bashir about not being noticed by his Academy rival , Elizabeth Lense , O ' Brien came close to admitting that he loved Bashir . On another occasion , O ' Brien inadvertently expressed the wish that Keiko was more like Bashir . O ' Brien was eventually able to accept that he could be close to both his friend and his wife . ( ) O ' Brien also thought very highly of Bashir . While he was talking about how much he loved his children , O ' Brien even told Bashir that he thought Julian would make a great father . Doctor Bashir jokingly admitted that he wasn ' t the family type . ( ) The friendship was strained at times . When Bashir and O ' Brien were trapped on a planet with some rogue Jem ' Hadar , Bashir decided to help their leader Goran ' Agar find out why he was no longer addicted to the white . O ' Brien was vehemently against such a proposal , noting that the Jem ' Hadar were enemies of the Federation , and that freeing them of the white would make them a larger threat to the Alpha Quadrant . He was further resentful when Bashir ordered him to help . On another occasion , Bashir and a group of genetically engineered Humans predicted that the Federation was doomed to lose the Dominion War . Miles was angry at the sheer arrogance shown by the group , noting that they were not as smart as they thought they were . ( ) The friendship helped the two through troubled times . When O ' Brien was given twenty years of prison memories for a crime he did not commit by the Argrathi and could not adjust , he attempted to kill himself . One of the false memories was that he had killed his best friend in prison , even admitting that had it been Bashir in the cell with him , he would have killed the doctor as well . It was Bashir who was able to talk him out of the attempt and get him help . ( ) Later , as Bashir became desperate to find a cure for Odo ' s morphogenic virus , O ' Brien came up with the scheme to lure a Section 31 operative onto the station , capture him , and then probe his mind for knowledge of the cure . Then , when Bashir decided to delve into Luther Sloan ' s dying mind for the knowledge , O ' Brien insisted on going with him , which proved critical in keeping Bashir focused on obtaining the cure even when faced with the possibility of acquiring information that could allow him to shut down Section 31 . ( ) Worf . Miles O ' Brien and Worf knew each other from their early days on the " Enterprise " , although their relationship was that of a noncom and his superior . The two would play together in the crew ' s poker games . O ' Brien participated in Wesley Crusher ' s Age of Ascension recreation for Worf , where he commented on the power of the Klingon painstik s . ( ) O ' Brien was the first person , besides Worf , to greet the Klingon ' s adoptive Human parents , upon their arrival on board the " Enterprise " , Worf ' s adopted father noting that he had served in O ' Brien ' s position during his own Starfleet career . ( ) Although Worf had to man the bridge at O ' Brien ' s wedding to Keiko , he gave O ' Brien a Klingon weapon as a wedding gift . In 2368 , when the " Enterprise " was damaged by a quantum filament , Worf was forced to deliver Keiko ' s baby daughter , Molly . He humorously noted that Molly resembled Miles . ( ) The friendship strengthened when Worf transferred to Deep Space 9 . O ' Brien was the first person to greet Worf when he arrived . Later he introduced Worf to the game of darts , describing it as " poker , but with pointed tips . " When Worf accepted the position of strategic operations officer ( with a change of uniform from yellow to red ) , O ' Brien commented how good Worf looked in red . ( ) When the " Defiant " was damaged by the Jem ' Hadar during their Karemma negotiations , and Worf found commanding the engineering team difficult , O ' Brien helped Worf take a different approach to command . ( ) When Worf discovered that the O ' Briens were having another child , he altered his holiday plans to coincide with the birth , just so he wouldn ' t have to deliver O ' Brien ' s baby ( as he did with Molly ) . ( ) During Worf ' s trial that demanded his extradition to the Klingon Empire , O ' Brien described Worf as " an honorable man " . In turn , Worf described O ' Brien as an " outstanding officer " and a friend , relaying their mutual respect out loud . ( ) Worf incited a riot against the Jem ' Hadar , Toman ' torax , in retaliation for threatening O ' Brien . ( ) In 2373 , Worf and O ' Brien participated in recovering a Jem ' Hadar ship from Torga IV . Although Worf believed that Enrique Muniz would not survive from his wounds , O ' Brien did not agree and clashed with Worf ' s pessimism . Worf was later proved right and Muñiz did pass away . Once the mission was over , O ' Brien and Worf performed the Klingon tradition of " ak ' voh " in front of Muñiz ' s casket . ( ) O ' Brien had to undergo a ritual fasting with Julian Bashir and Sisko as part of Worf ' s " Kal ' Hyah " ceremony , which was different than what he thought it would be . He couldn ' t last the four days ( even vowing to kill Worf at one point ) , and when he heard the wedding ceremony was called off , he and Bashir immediately ordered a large feast of Terran and Bajoran food . Sisko stopped them and helped put the wedding back on track . ( ) At one point , Worf and O ' Brien , while watching Jadzia and Quark playing a game of tongo against each other and a group of Ferengi waiters , Worf made a bet that Jadzia had the game in hand . He wagered to O ' Brien that if she won , he would owe Worf a bottle of bloodwine . If Jadzia lost , Worf would then owe the chief a bottle of Scotch whiskey . In the end , Worf ended up saying that he would need time to come up with O ' Brien ' s payment . ( ) After Jadzia Dax died at the hands of Gul Dukat , O ' Brien was one of the first people who attempted to cheer up Worf . While drinking bloodwine and reminiscing about old crewmates from the " Enterprise " ( most notably , Reginald Barclay ) , O ' Brien found out what was bothering Worf – the fact that his wife did not die an honorable death , and thus could not enter " Sto - vo - kor " . O ' Brien then directed Martok to help Worf , who assigned him the mission to destroy the Monac IV fleet yards . ( ) A short time later , O ' Brien helped Worf ease his hostility to Ezri . Over a bottle of bloodwine , O ' Brien asked how Jadzia would feel if she knew how poorly Worf treated Ezri . When Worf claimed that there was no way to know , O ' Brien refuted the claim , suggesting he talk to the one person Worf had been avoiding . After keeping her in Starfleet , Worf and O ' Brien attended Ezri ' s promotion party . ( ) When O ' Brien ' s authorization code was used to access sixteen cases of bloodwine sent to Martok by Sirella , Martok and Worf had to quiz O ' Brien on where the cases went . O ' Brien had to explain to Worf and Martok that Nog must have taken the bloodwine to barter for a graviton stabilizer . Worf and Martok gave O ' Brien one day to find the bloodwine . Fortunately , Nog had returned with 16 cases of 2309 bloodwine bought from his cousin Gant , an even better vintage than the ones Nog took . Both Klingons gave O ' Brien a bottle of the bloodwine as an " apology " . ( ) Benjamin Sisko . O ' Brien ' s relationship with Benjamin Sisko could be described as a classic example of a crewman ' s loyalty and devotion to a commander . And this relationship developed quickly . O ' Brien respected Sisko from the first , and Sisko came to rely on Miles to keep Deep Space 9 running in the earliest days of his command . Sisko was quick to reprimand O ' Brien , after the Tosk incident , even though he approved of O ' Brien ' s actions on a personal level . ( ) Aside from this incident , Sisko seemed to have developed a very casual friendship with O ' Brien , despite the difference in their ranks and the fact that Miles was an enlisted crewman and Sisko an officer . And O ' Brien was unswervingly loyal to his commander . They both would talk about their respective roles as fathers . ( ) Sisko verbally threatened the Cardassians should any harm come to O ' Brien , who was held under false charges . Upon concluding the Cardassians ' plot regarding the Maquis , he pulled a few strings and extended O ' Brien ' s vacation time . ( ) O ' Brien volunteered to remain behind on Deep Space 9 to help Sisko , Li Nalas , and a handful of others retain control of the station after Starfleet was ordered off by the Provisional Government , under the influence of The Circle . He did this even though it could have meant the end of his Starfleet career and over the strenuous objections of his wife . ( ) Sisko was sympathetic to O ' Brien after his daughter Molly was thrown in a time portal . Once the incident ended , he volunteered to represent his engineer at a Starfleet hearing , and defended his actions at a hearing . ( ) Odo . 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 . ( ) At one point , Garak makes mention that O ' Brien shares " human crime novels " with Odo ; he states that they may be influencing Odo ' s thinking . ( ) O ' Brien and Odo once went kayaking in a holosuite ; an activity Odo found " quite enjoyable " . ( ) Kira Nerys . O ' Brien ' s relationship with the Bajoran first officer of Deep Space Nine started out rocky . Kira did not trust Starfleet , or the presence of the Federation on DS9 . But , O ' Brien earned her trust , and her friendship . The turning point in O ' Brien ' s relationship with Kira came when he helped her rescue Li Nalas from a Cardassian prison camp . From this point , Kira began to view O ' Brien as someone she could trust , and someone she could rely on in a dangerous situation ( ) . Kira carried Miles and Keiko O ' Brien ' s baby to term following a runabout accident that threatened Keiko ' s pregnancy . The fetus was transferred to Kira ' s womb under the emergency circumstances so that both mother and child might live . During Kira ' s pregnancy , she and Miles formed a close , even intimate personal relationship . Kira was invited by Keiko to live in the O ' Brien ' s ' quarters , and Miles helped Kira with the pregnancy ' s physical discomfort with massages and other Bajoran treatments . The physical and emotional closeness of this time caused O ' Brien and Kira to struggle against romantic feelings that developed between them , although in the end they were able to put those aside and remain friends , Kira retaining an aunt - like relationship with O ' Brien ' s children . ( ) Interests and hobbies . During his childhood , Miles developed keen construction skills . Despite doing poorly in mechanical aptitude tests , he spent many hours constructing model starship engines , models of subspace transceiver assemblies and ships in a bottle . He also did a great deal of hiking , climbing mountains in his native Ireland . ( ; ; ) O ' Brien ' s one continuing passion was kayaking , and he frequently found himself visiting sickbay or the infirmary for shoulder injuries sustained during programs . ( ; ) This eventually resulted in humeral socket replacement surgery in 2371 ( although the injury that necessitated the operation was not sustained through the sport ) . This did not end O ' Brien ' s shoulder problems – he suffered a torn rotator cuff four years later , while practicing baseball with the Niners . ( ) He enjoyed singing while kayaking , which he felt helped establish a good paddling rhythm . ( ) Together with Julian Bashir , O ' Brien pursued several other hobbies like racquetball , darts and historical reenactments in the holosuite of events such as the Battle of Britain , Battle of Clontarf or the defending of the Alamo , of which he even created a detailed model in his quarters . ( " et . al " ) He maintained his love of music , playing the cello in a string quartet aboard the " Enterprise " . ( ) O ' Brien was also a fan of detective fiction novels , particularly Mickey Spillane and his character Mike Hammer , a preference he passed on to Odo , to whom he frequently loaned books . ( ) O ' Brien was literate in the Trill language . ( ) A favored drink of O ' Brien ' s was coffee : Jamaican blend , double - strong , double - sweet , as well as just black and double - sweet . ( ) O ' Brien was a fan of Starfleet combat ration s , and that those rations were the only thing that he missed about the Cardassian front . ( ; ) According to Sarina Douglas , she thought O ' Brien would be a fitting replacement for Greek god Atlas if he ever got tired , adding that " he would do it with a smile on his face . " ( ) Holograms . Miles O ' Brien has been holographically duplicated on a number of occasions . Appendices . Problematic rank history . The character of Miles O ' Brien , and the exact rank he held in " Star Trek " , has a history of its own spanning the length of the character ' s existence . In thirteen years of the character ' s appearances , only in the last four was his rank established to be presumably senior chief petty officer ( although this term was never directly used on screen ) . Through various other stages of the character ' s development , O ' Brien was referred to as a crewman , a lieutenant , and various script notes indicated he was a " warrant officer . " The novelization of indicated O ' Brien held a rank known as " ensign junior grade " . The exact history of O ' Brien ' s ranks are as follows : 1987 : Appears in and is referred to as " Conn " ( not as a name , but showing he was conducting the movements of the ship ) . In this episode , O ' Brien wears the single pip of a Starfleet ensign ( 1 ) and a red command division uniform . In he appears again , with no apparent insignia , credited as First Security Guard and in the corresponding yellow operations division uniform . 1988 : Appears in , credited as Transporter Chief . He wears the two pips of a Starfleet lieutenant ( 2 ) . In he appears wearing the same uniform and insignia as " The Child " and is directly addressed by Commander Riker as " lieutenant " , seemingly indicating that O ' Brien is an officer . 1989 : O ' Brien ' s surname is mentioned for the first time in . He is wearing the two pips of a Starfleet lieutenant again and is addressed as chief . 1989 : Appears in , again wearing two pips . Toward the end of the episode , then Lieutenant Junior Grade Worf gives him transporter coordinates . After entering them , Worf says " " I relieve you " " , to which O ' Brien replies , " " Well I . . . yes , lieutenant " " , indicating Worf ' s rank is superior to his own . ( It should be noted , however , there have been multiple examples in Starfleet of position occasionally trumping rank , such as a bridge officer being left in command of a ship , even when a superior officer is on duty in engineering ) . 1990 : Appears in and is addressed as " another chief petty officer " by Sergey Rozhenko , even though he is shown wearing lieutenant ' s pips , and is given a first ( and middle ) name , three years after his first appearance . From this point on , O ' Brien ' s character is developed as a senior enlisted member of the " Enterprise " crew , although he continued to wear the lieutenant ' s insignia . 1991 : Appears in wearing his usual uniform and insignia . At the end of the episode , O ' Brien wears a dress uniform also with the two pip insignia of a lieutenant . 1992 : Appears in where O ' Brien is given direct orders by Reginald Barclay ( who is a lieutenant junior grade ) thus firming up the idea that O ' Brien is a noncom as opposed to an commissioned officer . This episode marks the first time that O ' Brien wears the single hollow pip with his regular uniform ( 3 ) . ( The defines this as the insignia of a " chief warrant officer " , although the term is never used on - screen . ) 1993 : Appears in as " Chief of Operations " . For the next three years , O ' Brien wears a single hollow pip insignia with his rank again very much in question . Script notes from several Deep Space Nine episodes indicate he is a " warrant officer " , while the pilot ' s novel version states O ' Brien is an " Ensign Junior Grade " ( 3 ) . 1994 : Appears in where his title is stated to be senior chief specialist . He appears also in the past segment of wearing the single pip of a Starfleet ensign , which is consistent with what was worn during " Encounter at Farpoint " ( 1 ) . The " " incorrectly reports that O ' Brien wears a single hollow pip during the episode . 1995 : In , when the other officers are lamenting having to attend a formal Starfleet function , O ' Brien is asked if he would like to attend . He half - jokes , " " Full dress uniform , fine table linens , a different fork for every course ? No thanks , that ' s why I stayed an enlisted man . They don ' t expect me to show up for these formal dinners . " " 1995 : By the time of , O ' Brien has begun to wear a new insignia reminiscent of the chevron rank used by modern - day master chief petty officers in the US Navy ( 4 ) . In this episode , a Jem ' Hadar familiar with Starfleet insignia identifies it as a chief petty officer insignia . Presumably it was actually senior chief petty officer , as the word senior was used in " Shadowplay " , so the Jem ' Hadar presumably simply left out the distinction . His dress uniform in displays no rank insignia , but in it has the single hollow pip . Possible explanations for O ' Brien ' s various titles and insignia include : Some problems with assuming that O ' Brien is a Starfleet chief petty officer include :