في Red Sun Rising ، قبل 236 عامًا ، كانت جوزفين وعائلتها من بين العائلات الأصلية (The Primes ) التي استقرت في Sanctum كجزء من Mission Team Alpha . بصفته عالم أحياء مدربًا في مجال التصنيف ، كانت مهمة جوزي الأساسية هي دراسة وتصنيف النباتات والحيوانات على القمر. وجدت المكان آمنًا وهادئًا ، لذا اقترحت تسميته "Sanctum" - الجذر اللاتيني لـ "الملاذ". أثناء الخروج مع غابرييل سانتياغوخلال لقائهم الأول مع كسوف الشمس الأحمر ، كانت جوزفين أول من لاحظ أن شيئًا ما لم يكن صحيحًا عندما توقفت جميع الحشرات عن الحركة. ركضت عائدة نحو معسكرهم في الوقت الذي بدأ فيه سرب من الحشرات يهاجم. لسوء الحظ ، وجدت والدها يعاني من الذهان الناجم عن الخسوف الذي جعله ينقلب على أسرته. بدأ راسل بقتل الناس بمن فيهم ابنته جوزفين.

على مر السنين ، تمت إعادة جوزفين وغيرها من Primes عدة مرات باستخدام تقنية Mind Drive التي تنقل ذكريات وشخصيات Primes إلى أجسام مضيفة للأشخاص ذوي الدم الملكي .

في The Children of Gabriel ، يكشف راسل لايتبورن لكلارك جريفين أن ابنته جوزفين قُتلت في سقوط مأساوي قبل ستة أعوام من وصول كلارك.

في فيلم The Face Behind the Glass ، كان والدا جوزفين ، راسل وسيمون لايتبورن في أجساد مضيفي "الدم الملكي" (Nightblood) ، في أمس الحاجة إلى إعادتها. لقد كانوا ينتظرون أن تبلغ روز سن الرشد حتى يتمكنوا من استخدامها كمضيفة لجوزي ، ولكن تم اختطاف روز وقتلها على يد أبناء غابرييل . بعد اكتشاف أن كلارك لها دم ملكي ، تستغل عائلة لايتبورن لها عندما تكون مشلولة لإعادة جوزفين. قاموا بإدخال عقل جوزي في كلارك ، واستبدلوا ذكرياتها وشخصيتها بجوزفين. تستيقظ جوزفين في جسد كلارك خائفة في البداية ظنًا أنها كانت تسقط. بدأت اللعب بشعرها تمامًا كما اعتادت جوزي الأصلية.

في إنجيل جوزفين ، تكشف جوزي لوالديها أن كايلي هي التي قتلت مضيفها الأخير. هذا هو السبب في أن عائلة Kaylee سرقت Gagarin ، للهروب من Sanctum قبل أن يتم القبض عليهم. استدعى راسل وسيمون كايلي لاستجوابها حول هذا الموضوع. جوزي تقتل كايلي حتى تتساوى معها. بعد ذلك ، طلب والدا جوزي منها أن تظل بعيدة عن الأنظار وتتظاهر بأنها كلارك من أجل التجسس على ونكرو ومعرفة عدد الآخرين الذين لديهم دم ملكي . وهي تعيين اليشم كما حارسها الشخصي لأنها يخلط مع الأصدقاء كلارك. يبدأ أصدقاء كلارك في الشك عندما تتظاهر جوزفين بأنها كلارك ، وتسمح لمادي بالذهاب إلى المدرسة على الرغم من كلارك وبعد أن وافق جايا على أنه كان محفوفًا بالمخاطر. عندما تذهب لرؤية والدة كلارك آبي ، كادت تنفخ غلافها بتدوين الملاحظات بيدها اليمنى ، لأن كلارك أعسر. تغطي جوزفين خطأها بسرعة باستخدام معرفتها كعالمة أحياء لاقتراح حل لمشكلة غسيل الكلى التي يعاني منها ماركوس كين باستخدام حشرة Sanctum.

عندما لاحظت جوزي أن أصدقاء كلارك توجهوا إلى الغرفة حيث تقام طقوس حفل التسمية ، تتبعهم لإبقائهم تحت المراقبة. تحاول حثهم على المغادرة ، لكن جوردان وبيلامي وجايا يظلون مثابرين. تراقبهم وهم يكشفون عن الغرفة المليئة بالهياكل العظمية لجميع الأعداد السابقة. وجدوا بابًا سريًا لمعمل وجدوا فيه جهاز كمبيوتر به سجلات فيديو. أحدها عبارة عن سجل فيديو تجريبي اكتشف فيه صديق جوزي السابق غابرييل سانتياغو أخيرًا كيفية إعادة جوزي باستخدام Mind Drive.

After watching how Gabriel forced unwilling Nightbloods to become hosts for the Primes, Josephine doesn't seem concerned, which worries Clarke's friends. She learns that Madi is a Nightblood but sticks around to figure out how many more they have. When Murphy mentions that Clarke was turned into a Nightblood in a lab, Josephine figures out they can use that to make more hosts for the Primes. When she gets up to tell her parents, Bellamy becomes suspicious and confronts her. Bellamy's suspicions are confirmed when she struggles to understand Trigedasleng. Bellamy pins her against the wall and asks her who she is. Josephine knocks him out with a paralytic dart and reveals that she is Josephine Lightbourne. Heading to visit Abby, Josephine overhears her talking about her desperation save Kane and sees an opportunity since Abby is the key to making new Nightbloods. However, Josephine realizes that she needs to figure out how to blend in better first. She gets Murphy drunk before helping him figure out she's Josephine, confessing that her parents killed Clarke to bring her back. To get Murphy on her side, she asks him if he wants immortality.

In Memento Mori, Murphy fills Josephine in on Clarke's history, catching her up with how Clarke defeated A.L.I.E. However, Murphy is exhausted and notes Josephine's own sleeplessness, causing her to explain that its common the first few nights in a new host. Reminding Murphy of her promise of immortality through a Mind Drive, he quizzes her on what cards she will play against Abby, ending with the death of Jake Griffin. When Madi starts screaming, Murphy reminds Josephine she has to take care of "her" daughter and Josephine departs with the Mind Drives she promised for Murphy and Emori, stating that he has to get her past Abby before she will wipe her friends from them for him. Josephine finds Madi speaking Trig and Gaia explains that Sheidheda the Dark Commander is getting too strong and the must do the Seperation Ritual. Josephine snaps Madi out of it and tries to convince her that it wasn't real, worrying both Gaia and Madi as they know it was a memory. Gaia chastises Josephine for her actions which could've caused permanent damage to Madi and becomes concerned by Josephine's nonchalant attitude towards the episode. Josephine returns to Murphy, observed by Gaia, who silently shakes his head at her. Josephine then returns to work with Murphy.

The next morning, Josephine reviews the pictures of Clarke's friends as Murphy sleeps before Echo, Emori and Raven Reyes enter. Having learned the truth about the Primes from Jordan Green and concerned about Bellamy's disappearance, Clarke's friends declare the Primes murderers and body snatchers and attempt to leave. Josephine claims that Bellamy is scouting for a location for a new compound for Wonkru and they need to continue to cooperate with the people of Sanctum. Clarke's friends, particularly Raven and Echo reluctantly agree with Josephine noting that Echo will be a problem. Murphy realizes that Josephine is lying about Bellamy which she admits to, stating that she hasn't killed him but will if she has to. Murphy warns that if Bellamy knows Clarke is dead, then it is all for nothing and she might as well just kill them now. Josephine suggests instead waiting until the foraging party returns so that Murphy can have time to get Bellamy on their side. Josephine orders Jade to follow Echo and sends Murphy, pretending to be a prisoner, to convince Bellamy to side with them.

Later, Josephine approaches a despondent Abby and asks if she has had any luck solving "the Kane problem." Though confused by her wording, Abby states that she hasn't and Josephine reveals that the Primes have a way to save Kane, but Abby will have to turn him into a Nightblood first. Josephine invites Abby inside to see what she means. Josephine shows Abby a Mind Drive and states that in exchange for showing the Primes how to make Nightblood, she can use the Mind Drive to save Kane by making him a Nightblood and downloading his mind into the Mind Drive. Abby is conflicted since Kane's mind would go into another person's body and Josephine reminds them of the worse things they've done such as the Culling on the Ark, Mount Weather and the events in Becca's lab. When Abby insists that they did that to survive, Josephine states that they did survive and now have the chance to get their humanity back. Josephine tells Abby that people would volunteer to be hosts and they can bring all of the Primes back at once. However, her behavior causes Abby to finally realize that "Clarke" is acting strangely and Josephine covers by claiming that they need Kane for his goodness to save them as he did by negotiating peace in Polis. Josephine uses Abby's guilt over Jake's death and her addiction causing Kane's injuries to get Abby to finally agree to help the Primes.

Having succeeded in getting Abby's help, Josephine approaches Simone to erase the Lee family from their Mind Drives in order to keep her promises to Murphy and Abby. Josephine justifies her choice of Simone rather than Russell as Russell thinking with his heart while they have to be practical: with no hosts, they either die in their current bodies or they wipe the Lee's and live forever. Once Abby shows Simone how to make Nightblood, they never have to wait for new hosts again and the best part is there will be no more Nulls, no Oblation and anyone can be a host, giving them the genetic pick of the litter. Reluctantly, Simone erases the Lee family from their Mind Drives using an Eligius computer to Josephine's pleasure.

After Abby leaves for Eligius IV, Josephine approaches Bellamy herself in an attempt to convince him to accept the deal of the Primes help in building a compound for the people of Earth if they don't retaliate for Clarke's death. Josephine claims that they are both struggling with the situation and she is hoping they can help each other through it. As she approaches Bellamy with a knife to kill him, Murphy interrupts with Russell. Russell angrily confronts his daughter over her callousness towards Bellamy's grief over Clarke while Josephine mocks Russell's remorse over Clarke's death. As Russell attempts to convince Bellamy, Josephine cuts Bellamy free who attacks Russell so that she can make the point that Clarke and her friends only know violence. Josephine suggests that Bellamy kill Russell if he needs, but let the violence end there, "an eye for an eye." After a moment, Bellamy releases Russell and a pleased Josephine hands Murphy the two Mind Drives she promised him.

That night, pleased with the events of the day, Josephine finally goes to sleep. After she falls asleep, Clarke, still alive inside of her body, awakens in a projection of her cell on the Ark.

In Nevermind, Clarke, who survived due to her experiences with A.L.I.E., works to wrest control of her body back from Josephine while she is sleeping by traveling through Josephine's memories with a manifestation of Monty Green. Clarke finds the one traumatic memory Josephine couldn't face, where her stalker Dave committed suicide when Josephine wouldn't talk to him. Clarke is confronted by Josephine, who shoves Clarke back into her mind palace and wakes up with a nosebleed. Josephine attends a meeting with her father, Bellamy and Nathan Miller, but fails to realize that Clarke has managed to retake control of one finger and make Josephine tap out a Morse code message on her arm that Clarke is still alive. Bellamy sees the message and quickly grasps the significance, while Josephine warns Russell that Clarke is still alive. However, she now knows how to get rid of Clarke for good.

In The Old Man and the Anomaly, Russell determines that they have 36 hours before Clarke's body burns out from the strain. Josephine decides to stay awake until they can get rid of Clarke for good, but Russell instead sees it as an opportunity to restore the wrong they did by resurrecting Josephine through Clarke. Russell suggests removing Josephine's Mind Drive and restoring Clarke to her own body while they find a new willing host for Josephine, since Abby has replicated the Nightblood serum. Josephine, however, is unwilling to give up her host and unsuccessfully tries to talk Russell out of it.

Unwilling to give up Clarke's body, Josephine enlists Murphy, Emori and Ryker to help her in secret, blackmailing Ryker with the knowledge that he helped Gabriel escape to force his compliance. Though Emori originally agrees to help, she eventually betrays Josephine and lures her and Murphy into a field; there they are joined by Bellamy and Echo, who plan to use an EMP to disable Josephine and have Eric Jackson remove the Mind Drive. Josephine takes Murphy hostage to force them to back down, but Murphy directs them instead to take Josephine to the Children of Gabriel to get rid of her. With Sanctum guards approaching, Josephine slices open Murphy's leg and tries to use the distraction to escape but is caught by Bellamy and restrained. As the others remain behind, Bellamy uses the EMP to temporarily disable the radiation fence. He drags a resisting Josephine through to take her to the Children of Gabriel.

At the same time, on his approach to the Temporal Anomaly, Gabriel has various hallucinations of Josephine in her original body. Gabriel implies that Josephine is both his darkest fear and deepest desire.

In What You Take With You, Bellamy seeks out the Children of Gabriel to remove Josephine from Clarke. However, Josephine's condition continues to deteriorate, causing a seizure. The two are captured shortly thereafter by the Children of Gabriel, who leave to send a message to Gabriel. Bellamy notes Josephine's reaction to that name and Josephine admits to being in love with Gabriel for 236 years, despite the fact that Gabriel has been trying to kill her for the last 70 of those years. Due to wall in their mind being almost gone, Clarke is able to hear their conversation and uses Morse code to tap out "boohoo" to Josephine, which she now understands. However, Josephine refuses to relinquish control so that Bellamy can talk with Clarke. With their minds beginning the merge, Josephine gains some of Clarke's knowledge in regards to Bellamy and their relationship. Bellamy explains that he intends to trade Josephine's Mind Drive to Russell for peace with the Sanctum citizens, something Josephine sees as impossible.

With Sanctum guards approaching, the Children return and realize that Josephine is a Nightblood and a Prime. After Bellamy identifies her, the Children prepare to execute Josephine. At the last moment, Josephine relinquishes control to Clarke who is able to break free. Clarke explains to Bellamy that Josephine recognized that her choices were give Clarke control or get her head chopped off. After Clarke knocks Jade unconscious, a manifestation of Josephine in her original body appears to her. Josephine explains that due to how far their minds are merging, Clarke can now see her in the waking world. Josephine urges Clarke to relinquish control so Josephine can return to Sanctum, but she refuses. Instead, Clarke sends a message to Gabriel, who receives it alongside Octavia Blake. Tapping into Josephine's knowledge of motorcycles, Clarke drives off to find Gabriel taunting Josephine, "sucks doesn't it?" in Mandarin.

In Matryoshka, Josephine continues communicating with Clarke as she tries to find Gabriel before collapsing. As Sanctum guards approach, Clarke convinces Josephine to help her hide in an old blind once used by Gabriel and Josephine to observe Sanctum's wildlife. However, Clarke experiences another seizure, rendering her unconscious as Josephine desperately tries to soothe her.

After the seizure ends, Clarke awakens in her Mindspace to find that it has merged with Josephine's completely. With their condition worsening, Clarke threatens to shoot Josephine, who warns Clarke that if she dies this time with their minds combined, Josephine could be gone for good. Instead, Clarke comes up with the idea of floating some of Josephine's memories to help separate their minds and buy them some time. With the Mind Drive approaching critical systems failure, Josephine agrees and loses the memories that Clarke floats. She is unable to remember what she lost, just that she did lose them. Exploring Josephine's memories to find ones to float, they come across one of Josephine and Gabriel dancing after their first resurrection. Seeing how emotional it makes Josephine, Clarke allows her to keep the memory; Josephine admits that she wasn't always the evil person she became, causing Clarke to sympathize with her. As Josephine opens another book, she relives the memory of her first death, resulting in Russell's axe manifesting in the Mindspace. Seeing how badly the Mindspace has deteriorated, Clarke floats everything, causing Josephine to disappear.

In the real world, Clarke's body is surrounded by vines, and she is nearly choked to death before being rescued by Gabriel and Octavia. Josephine reveals that she has regained control over Clarke's body and is reunited with Gabriel for the first time in 70 years. They are soon after captured by Sanctum guards led by Jade, causing Josephine to order Gabriel's capture and the death of Octavia. However, Bellamy reveals himself amongst the guards, kills the others and sends Jade back to Sanctum with a threat. With Clarke's body experiencing another seizure, Gabriel takes them back to the Verge, where he prepares to temporarily stop Clarke's heart so that Josephine's mind will download into her Mind Drive to be removed. Josephine tries to convince Gabriel not to go through with it so they can finally be together, while Bellamy still wants to return Josephine to Sanctum. However, Josephine knows that Gabriel doesn't want her to resurrect again as he knows that another innocent life could be taken if she was to be resurrected. Gabriel tearfully stops Clarke's heart and removes the Mind Drive, but he can't revive Clarke.

In her mind, Clarke is confronted by Josephine, who reveals that she managed to latch on to the neural mesh in Clarke's mind to prevent the download. Josephine slits Clarke's throat with Russell's axe, declares that Sanctum is hers and explains that she knew that if Clarke came back, she would kill everyone inside Sanctum. Unwilling to let Clarke go, Bellamy desperately tries to revive her, urging Clarke to fight. Hearing Bellamy's cries, Clarke grabs the axe and swings it through Josephine, destroying her. In the real world, Clarke regains consciousness while the brain wave pattern representing Josephine flatlines on Gabriel's EEG.

In Ashes to Ashes, Clarke, Bellamy, Octavia and Gabriel try to come up with a plan to defeat the remaining Primes. As they prepare a Red Sun toxin bomb, Clarke realizes that Josephine was right about what they would do to Sanctum. She comments that it was just like Mount Weather all over again and is inspired to come up with a new, less lethal plan. Clarke comes up with the idea to pose as Josephine to sneak into Sanctum and take down the shield, while the others simulate a Red Sun eclipse to cause an evacuation. When Jade and Murphy arrive, Clarke is able to perfectly imitate Josephine and fool them and Russell to get into Sanctum. Clarke's story for her lack of a Mind Drive is just what Josephine actually did: she used Clarke's neural mesh to hang on inside of her head when the Mind Drive was removed. Clarke, posing as Josephine, claims that she won the fight and killed Clarke in the Mindspace. Clarke is also forced to lie to Madi, making Madi even more enraged at the thought that her mother truly is dead.

In Adjustment Protocol, Clarke continues her masquerade as Josephine, which forces her to lie to her family and friends about her continued survival. Clarke's act as Josephine proves to be so good that even Abby falls for it and bursts into tears at the idea that her child is truly dead. However, when they are alone, Clarke reveals the truth to Abby, Raven and Eric Jackson. Clarke successfully continues her masquerade as Josephine, even fooling Simone when she is resurrected in the host of Abigail Griffin. Clarke is able to pass off her tears as Josephine being enraged at the betrayal of Gabriel, who has been captured. Before departing with the other Primes for Eligius IV, Clarke inadvertently reveals the truth to Murphy and Emori when she slips up and calls Murphy by his last name instead of John, as Josephine would do. Relieved by Clarke's survival, Murphy informs Clarke that Josephine called him John.

In The Blood of Sanctum, Clarke continues her masquerade as Josephine until Russell and Simone plot to mind wipe all of the sleeping Wonkru members. When Clarke refuses and pulls a gun on them, Josephine's parents realize the truth and Russell bursts into tears. Walking away with the mind wipe solution, Clarke tells them that "believe it or not, I am sorry for your loss." Josephine's death, along with the later deaths of Simone, Miranda, Caleb and Jasmine at Clarke's hands, drive Russell to seek revenge for the loss of his entire family.