Rachel was the first female clone raised self-aware of her origin. Susan and Ethan Duncan are her parents, however, they faked their deaths when Rachel was six-years-old and turned her over to the DYAD Institute to be reared by Neolution. Raised as a corporate cutthroat, Rachel learned to make ruthless decisions toward Neolution’s end goal of creating a ‘better human,’ but growing up this way only served to bolster her desire for power and harden her against her sisters. Stripped of family, Rachel’s one weakness is her blinding hatred of Sarah and jealousy of her motherhood. After suffering brain damage at Sarah’s hands, Rachel was brought to a mysterious headquarters where she was reunited with her mother. As much as Rachel longed for this possibility, she loathes Susan for abandoning her. As she recovers, she makes gradual steps in repairing their relationship.
In “Unconscious Selection”, Rachel is first seen when Aldous Leekie calls to tell her that Sarah Manning hasn’t shown up to bring Helena to him. She simply tells him that blood is thicker than he thinks and hangs up. Her back is turned but the reflection of her face is vaguely seen in a window.
In Endless Forms Most Beautiful, Sarah is taken out of police custody by Daniel Rosen and brought to Rachel at the Dyad Institute. Rachel tries to get Sarah to sign a contract with the promise of answers and protection for Sarah and Kira. When Sarah refuses, Rachel asks her to take 24 hours to reconsider. Later, Sarah calls Rachel and tells her that she doesn’t want Kira to live the way she has, to which Rachel agrees and Sarah agrees to come in. When Alison signs her contract and emails it to Rachel, Rachel tells Rosen, “one down, two to go.” When Cosima Niehaus tells Sarah that Rachel’s offer of freedom is a lie, that all the clones were patented, Sarah sends Rachel a text message saying “Up yours, Proclone” and runs to get to Kira. Rachel makes a phone call and says, “You know what to do.” It can be speculated that Rachel initiated a kidnapping attempt of Kira and Mrs. S.
In “Nature Under Constraint and Vexed”, while Sarah is on the run from Dyad, Rachel calls Sarah using Paul’s phone and tells her that Sarah can see Kira and Mrs. S again if she surrenders herself. Later, Rachel tells Paul that he is in fortunate position because he knows how Sarah thinks. She then goes into Leekie’s office and tells him that she needs his office for “both of the Koreas.” She then asks Paul if he’s ever been to Taiwan and if he speaks Mandarin. He answers no to both. She tells him to pack a bag and that they leave on Tuesday. When Paul leaves, Leekie asks Rachel, while she ties his bow tie, if she actually kidnapped Kira and Mrs. S. She tells him the less he knows, the better. He asks if they even need Sarah and she tells him that they do. She tells him that Rosen will recover Sarah and that he has to prepare for the night’s party. During the Dyad party, Sarah goes dressed as Cosima and goes down to Rachel’s office. Without turning to see who’s entered her office, Rachel knows it is Sarah. When Sarah demands to see her daughter, holding a gun, Rachel tells her that when her people arrived at Mrs. S’s house, they were already gone. Rachel tells her calmly, “You’re not going to shoot me, Sarah.” Sarah then shoots a glass plant holder very close to Rachel’s head, making a scared Rachel back away from her. Rachel tells Sarah that there are others after the clones and that together they can find Kira. Sarah strikes Rachel across the face and knocks Rachel to the ground. Sarah kneels down and holds the gun to Rachel’s face. Rachel tells her that nobody lays hands on her, then Sarah tells her that Rachel doesn’t own Sarah and the other clones. Paul comes in with his gun drawn and tells Sarah to put her gun down. Rachel gets a look of relief and then smirks at Sarah. Sarah then hits Rachel across the face with her gun and Rachel falls unconscious.
In “Governed by Sound Reason and True Religion”, Rachel walks into Cosima’s lab at Dyad when she’s making out with Delphine. Rachel and Cosima introduce themselves. Rachel tells Delphine that she’ll have to sign a new confidentiality agreement and dismisses her. Rachel shows Cosima the results of her latest medical exam from University of Minnesota. It shows a high lymphocyte count like Katja Obinger. Rachel gives her Katja’s data. When Cosima asks to examine the original genome, Rachel tells her that is impossible and that Cosima’s health problems stem from the cloning procedure. She then gives her data on Sarah’s upbringing and her sequenced genome. Rachel wants to know why Sarah is different from all the others.
In “Ipsa Scientia Potestas Est”, Rachel comes into her room where it is being cleaned after Daniel being killed by Helena. Leekie tries to dissuade her, but Rachel wishes to see what Helena did. Rachel bends over Daniel’s body and closes his eyes. Paul tells her that Sarah didn’t kill him; Rachel recognizes Helena’s handiwork. Rachel looks disturbed when she notices one of her videotapes in the VCR. Leekie tells her that all this is a result of her heavy-handedness. She tells him that she’s only begun. Later, Rachel is in her office with Paul and Leekie. She tells Paul that she needs a new monitor now that Daniel is dead. She tells him that even though she has been self-aware since childhood, she is not exempt from the program. After Leekie tells her that he’s had some success in creating a cure for Cosima’s illness, she tells him to halt the test; until Sarah gives herself up, Cosima will suffer. While watching the Cambridge 1991 videotape that Sarah looked at, Rachel tells Paul that Sarah’s trying to learn everything about her, like Rachel is trying to learn everything about Sarah. She also tells Paul that even though he reports her data to Leekie, he works for her. She tells him that when her adoptive parents died, Leekie became like a guardian to her. Rachel wants to know if Cal Morrison is Kira’s father; Paul tells her that the timeline fits. She then gives Paul the gun that Daniel used to murder Officer Tom Bowman with. It is assumed that she has him frame Felix for the murder. Later that night, Rachel has Paul in her apartment and has sex with him. Little does she know that she is almost killed by Helena until Sarah convinces her not to.
In “Knowledge of Causes, and Secret Motion of Things”, comes to Mrs. S’s house with Paul to meet with Ethan Duncan, her adoptive father, who she assumed had died in a fire years earlier. Mrs. S tells Rachel that she has 15 minutes to talk with him and that if anyone makes a move on her house, she will kill Ethan. Rachel sits at the kitchen table with Ethan and he explains to her what really happened to her adoptive mother, Susan Duncan. Ethan asks Rachel to forgive him and she starts crying. Later, at the Dyad Institute, Rachel is standing in her office when Leekie enters. Rachel tells him that her father sends his regards. Realizing that Rachel knows the truth about her parents, Leekie tells her that he had no choice because the Duncans were going to run away with Rachel and because they set the science of cloning back decades. While Leekie is standing next to her, Rachel calls Marion Bowles on speakerphone where they talk about how it has been arranged for Leekie to be killed. After hanging up, Rachel tells a scared Leekie to leave and that if he doesn’t get in his car or go home, he might survive. She tells him that it’s foolish to help him but she does it because Leekie raised her. Leekie lightly kisses her on the forehead and hurries from the office. Leekie is accidentally shot and killed by Donnie Hendrix in his car, and the information of how he died is kept from Rachel.
In “Variable and Full of Perturbation”, she invites Ethan to Dyad and asks him about the clones’ biology, specifically why Sarah can bear children and the others cannot. He reveals to her that because all of the clones were “barren by design,” Sarah was a “failure, not a success.” She is angered and upset by this information, but does not show it; so she imagines throwing a fit in Leekie’s office, crying and breaking things.
In “Things Which Have Never Yet Been Done”, Rachel promotes Delphine to Interim Director of the Program in Leekie’s absence. Rachel tells Delphine to persuade Sarah to allow Kira to donate bone marrow, which would save Cosima’s life (Cosima had coughed up a severe amount of blood and fallen to the ground in a seizure in the previous episode, the disease spreading further through her body). Sarah agrees. Rachel meets with Dr. Marion Bowles and the two have a passive-aggressive conversation regarding Rachel’s new knowledge of her family, appointing Delphine as chair of the program, and the question of whether Rachel is in control of Sarah. Rachel goes into her viewing room to watch old family videos of her with the Duncans; she first laughs with joy at the happy family, drinking a martini, but then she begins to cry out of sadness. She also slaps herself while saying the words “stupid” over and over again, beginning at first with gentle hits but then progressing to more firm ones. She then looks longingly at photos of Sarah and Kira together. She then calls a man named Dr. Nealon asking for his “expertise”, while putting on a leather hooded coat. Rachel then invites Delphine back to Leekie’s office (which she is currently occupying), where Delphine sees an email containing information about a Dyad asset whom she saw with Mrs. S, Sarah, and Felix. She then masquerades as Sarah, sedating Felix and taking Kira back to Dyad. She holds Kira in a special room, adorned all in pink and “girly” decor. Kira is afraid and Rachel tells her that she “may grow to like it here, just as I [she] did.”
In “By Means Which Have Never Yet Been Tried”, Sarah gives herself up to Dyad in order to get Kira back. Rachel, in an attempt to keep her from helping the clones, tells Delphine that she will be transferring to Frankfurt, Germany. Rachel interacts with Kira, trying to turn her against her mother, as Sarah watches through a one way mirror. Rachel had taken her father prisoner and is watching family videos with him in the viewing room. She pours them tea and he uses his own tea bag, laced with poison so he may kill himself before he reveals any vital information. He dies as he says, “my poor, poor Rachel,” and she tearfully, angrily, and violently begs him not to leave her again. As Sarah is being prepared for her oophorectomy, to remove one of her ovaries, Rachel asks her where Ethan’s key to the synthetic sequences is. Sarah tells her that she does not know, but Rachel does not believe it. She destroys Kira’s bone marrow one by one. As Rachel is about to leave, Sarah shoots her in the eye with a pencil, using a gun fashioned out of a fire extinguisher created by Scott and Cosima.
In the “The Weight of This Combination”, it is revealed that Rachel survived the pencil through her eye as she receives surgery for its removal. Dr. Nealon informs Delphine that Rachel’s left eye is lost and that she has sustained damage to her frontal lobe. Though impairment is unknown at this point, it appears that Rachel is suffering from signs of apraxia of speech, as she is able to recall her memories but experiences difficulty in verbalizing her thoughts. Delphine interrogates Rachel by painfully squeezing her left eye socket in order to learn more about Ferdinand’s agenda with Dyad.
In “Certain Agony of the Battlefield”, she is seen painting. She is still having trouble forming words, as we see when Felix, desperate to find Sarah, attempts to interrogate Rachel about Castor. When she tries to stutter the word “rumors”, he thumps her on the head with her paintbrush and says Castor isn’t rumors; it is very real and they have Sarah. He paints her eye patch blue, and Rachel says she won’t help him if he humiliates her. She is last seen alone and crying while painting a blue symbol like a line between two small circles, while looking at a picture of her younger self and her dad.