Personal life and family
Keiko had a strong bond with her family and past; as a child, she used to help her grandmother, whom she called obachan (Affectionate Japanese term for "grandmother"), with her Japanese brush writing or calligraphy. Young Keiko would fill an old chipped cup with water and bring it to the table for her grandmother to use for cleaning the ink brushes. Keiko would sit beside her and watch the most beautiful characters come from her brush – the whole time, she would hum to herself. (TNG: "Violations")
Keiko was introduced to Miles O'Brien by their mutual friend, Data. (TNG: "Data's Day") While on Earth together, Miles and Keiko visited McKinley Park, where Miles gave Keiko a gold bracelet. (TNG: "Power Play") The two eventually wed aboard the Enterprise-D in a wedding ceremony that combined Irish and Japanese traditions. Data served as the "father of the bride." (TNG: "Data's Day")
One of Keiko's favorite foods was plankton loaf with kelp buds and sea berries. Following her marriage to Miles, she prepared a plankton loaf for lunch one day, much to the dismay of Miles. (TNG: "The Wounded")
Together, Miles and Keiko O'Brien had their first child, Molly, who was born in early 2368. Keiko gave birth to the child in the Enterprise's Ten Forward lounge during a ship-wide systems failure. Worf coached Keiko during her labor and later delivered the baby. (TNG: "Disaster", "The Game")
Keiko was assigned to the USS Enterprise-D as a botanist, working primarily in the arboretum. (TNG: "Data's Day") She was also the head of the biology lab, when the Enterprise got caught in the Tyken's Rift. In mid-2368, Keiko was assisted by young Clara Sutter in planting several nasturtiums. (TNG: "Night Terrors", "Imaginary Friend")
For years, Keiko saw an old cup in her memory, but could never recall what it was or why it was important. Following an encounter with a Ullian named Tarmin, a telepathic historian, she was able to recall the significance of the cup – she thought that it was a wonderful experience. Following a series of telepathically-induced comas, Doctors Crusher and Martin did a neurological work-up on Keiko, since she was the only person aboard the Enterprise to experience the memory probe, in order to see if there were any residual effects from her experience. (TNG: "Violations")
In 2369, Keiko, Guinan, Ro Laren and Jean-Luc Picard visited the planet Marlonia, where Keiko found a specimen of Draebidium calimus, which she brought back to the Enterprise on her return trip. Moments before docking on the Enterprise, their shuttlecraft, Fermi, became enveloped in an energy field, and their subsequent emergency transport caused the group to be transformed into children. She was eventually returned to her normal state after she and her transformed colleagues helped to retake the ship from a group of renegade Ferengi. Keiko was particularly grateful to be returned to her normal adult self because while she was transformed into a child, her own daughter Molly didn't recognize her. (TNG: "Rascals")
Deep Space 9
On DS9, she found there was no need for a botanist, so with the permission of Benjamin Sisko, she opened a school for the children living on the station. (DS9: "A Man Alone") Within a few weeks of opening her classroom, she took her eleven students on a field trip to Bajor to visit the grain processing center in Lasuma. (DS9: "Dramatis Personae") Later that year, the school became embroiled in a dispute with the Bajorans. They believed that Keiko was teaching her Bajoran pupils that the Prophets were only "wormhole aliens". Keiko argued that it was her duty to expose students to knowledge, not to hide it from them, and refused to teach about the Prophets. The school was then destroyed by a bomb; fortunately, no one was in the school at the time. Commander Sisko held Vedek Winn responsible for the bombing. (DS9: "In the Hands of the Prophets") Keiko eventually closed the school down because the remaining Bajoran children left, leaving only "Jake, Nog, and a lot of empty chairs" (it's assumed the school was rebuilt after the bombing, otherwise she would have nothing to close down). (DS9: "The House of Quark")
In early 2370, when Bajor was on the verge of revolution, Keiko and Molly were evacuated to the Korat system. (DS9: "The Siege") Several weeks later, Keiko invited the Cardassian youth, Rugal, to move in with her family. (DS9: "Cardassians") Later that year, Keiko was gone for over a period of a week, attending a hydroponics conference on Rigel IV. (DS9: "The Wire")
When Miles believed that he was getting old, after Bashir destroyed him in a racquetball game, Keiko encouraged him to train and beat Bashir in their upcoming match that was being staged by Quark. Neither knew that Quark had fixed the game in Miles' favor in order to clean up on the wagers that were heavy in Bashir's favor. (DS9: "Rivals")
Miles had been reported killed in an explosion while destroying biogenic weapons for two alien races. Keiko viewed the tape of the incident and was convinced that the tape was a fake. Miles was shown drinking coffee in the afternoon, and she insisted that he never drank coffee at that time of day. This caused Sisko to investigate and find out that Miles was alive and that the races were trying to kill him in order that no one would know the secrets of the bio-weapons. Ironically, even though Keiko's suspicions proved correct, she later found out that Miles drank coffee in the afternoon all the time. (DS9: "Armageddon Game")
Miles was replaced by a replica during arrangements for a peace conference. He had been captured by rebels on Parada and his duplicate was programmed to assassinate one of the delegates. Keiko knew about the switch, but had to pretend that she did not so the duplicate would lead them to the real O'Brien. (DS9: "Whispers")
In 2371, Keiko joined an agrobiology expedition on Bajor, where she served as chief botanist. It was projected to be a six-month expedition and its first study region was the Janitza Mountains. (DS9: "The House of Quark", "Civil Defense", "Fascination") While Keiko was on Bajor, Miles began to focus more on his hobbies to allow time to pass quicker, including playing more racquetball and picking up the game of darts. (DS9: "Prophet Motive")
In early 2372, Keiko and Miles got into an argument because Miles set up a workshop in their bedroom. Miles justified his decision by stating that, since his wife was only on the station a few days at a time, he was the one who is really living in the quarters. Therefore, having a workshop in his bedroom was his right. Keiko saw this as Miles trying to "live like a bachelor again", and that he was living a "subconscious desire" to push her out of their quarters. (DS9: "Hippocratic Oath")
In 2372, Miles was arrested by the Argrathi on charges of espionage and subjected his mind to altering that implanted twenty years of prison into his synaptic pathways. Keiko had a very difficult time in trying to make him comfortable and readjust to a normal life. (DS9: "Hard Time")
Keiko ended her work on Bajor in 2372 and returned to Deep Space 9, after becoming pregnant with the O'Briens' second child. Keiko, however, was hurt in a shuttle accident and the child had to be relocated into Kira's womb in order to save Keiko and the child's life. (DS9: "Accession", "Body Parts") The child, Kirayoshi, was born in 2373. (DS9: "The Begotten")
Keiko's body was taken over by a Pah-wraith who threatened to kill her if O'Brien did not help it destroy the wormhole. The Pah-wraith forced O'Brien to convert the station into a gigantic chroniton emitter. Miles took Keiko (possessed by the Pah-wraith) to a runabout. Once in position near the wormhole, Miles activated the emitters on the station, but targeted the runabout instead of the wormhole, instantly killing the Pah-wraith inhabiting Keiko's body. (DS9: "The Assignment")
When war with the Dominion was almost a certainty by the end of the year, Keiko and her children semi-permanently left the station to live on Earth through the Dominion War. (DS9: "Call to Arms", "Change of Heart") They returned by the end of 2374. (DS9: "Time's Orphan")
Keiko had to deal with the loss of Molly who, while on a picnic on Golana, fell through a time portal three hundred years into the past. Molly returned as an eighteen-year-old who had grown up in a prehistoric era and could not adjust to the modern era. Keiko and Miles let her return through the portal, where the older Molly found her younger self and returned young Molly to her parents. (DS9: "Time's Orphan")
The family would remain together aboard DS9 throughout the remainder of the war. Miles turned down a visit to the holosuite with Bashir in favor of having dinner with his family in early 2375. (DS9: "Chrysalis")
Keiko O'Brien was portrayed by Rosalind Chao. The young Keiko in the episode "Rascals" was played by Caroline Junko King and Dawn Cleveland portrayed Keiko's hands during the flashback sequence in "Violations".
- "A Man Alone" (Season 1)
- "If Wishes Were Horses"
- "In the Hands of the Prophets"
- "The Siege" (Season 2)
- "Armageddon Game"
- "The House of Quark" (Season 3)
- "Accession" (Season 4)
- "Hard Time"
- "Body Parts"
- "Looking for par'Mach in All the Wrong Places" (Season 5)
- "The Assignment"
- "The Begotten"
- "Time's Orphan" (Season 6)
- "What You Leave Behind" (Season 7)
- TNG: "Imaginary Friend"
- "Civil Defense"
- "Prophet Motive"
- "The Way of the Warrior"
- "Hippocratic Oath"
- "To the Death"
- "Broken Link"
- "Apocalypse Rising"
- "Nor the Battle to the Strong"
- "Trials and Tribble-ations"
- "The Darkness and the Light"
- "Ties of Blood and Water"
- "Children of Time"
- "Call to Arms"
- "You Are Cordially Invited"
- "Change of Heart"
- "His Way"
- "Tears of the Prophets"
- "Tacking Into the Wind"
- "Extreme Measures"