During her childhood, Jac lived with several foster families who grew tired of her demeanour. According to her, she was ostracised at medical school for her talent, and her colleagues at the firms she worked at regularly considered her a threat. (HC: "Paranoid Android")
Locuming on Keller
On 21 November 2005, Jac - a locum registrar in general surgery - arrived on Holby City Hospital's Keller Ward to assist with performing a hemicorporectomy on Billy Finch, but Billy crashed his motorbike before undergoing surgery. Consultant Ric Griffin was forced to postpone the operation, and the multi-disciplinary team warned the surgeons that the hemicorporectomy would not be rescheduled due to its financial cost. Determined to allow the procedure to go ahead to impress her peers and secure a full-time placement at the hospital, Jac decided to break the rules and brought Billy's wife Melissa to the multi-disciplinary meeting. Swayed by Melissa's emotional appeal, the team decided to go ahead with the operation. The next day, as fellow registrar Diane Lloyd was busy assisting on the Maternity Ward, Jac volunteered to assume her role in Billy's operation. Following the successful completion of the operation, Jac confronted Ric about her remaining on his surgical team full-time, but Ric declined. (HC: "Bird on a Wire")
On 17 January 2006, due to a shortage of beds at St James' Hospital, Jac returned to Keller with a patient with ulcerative colitis named Leon. Jac and Diane clashed over how to treat Leon's condition; Diane was keen to avoid having to fit Leon with an ileostomy bag, but Leon's bowel was later deemed untenable, so Jac's approach was favoured. (HC: "Yesterday Once More") The following week, Jac discovered that there was a vacancy for a permanent registrar position on Keller and expressed her interest in it to Ric who was impressed with her mentoring skills after working well with medical student Matt Parker. (HC: "Brother's Keeper")
Competing for the consultant post
By 2 February, Jac had convinced Ric to give her the full-time registrar job. In theatre, Ric informed Jac that there was a vacant consultant post, and Jac expressed a keen interest in applying. Later that day, after Jac lied about being familiar with performing a partial hepatectomy and took credit for the surgery's success, Diane decided to compete against her for the post. (HC: "I'll Be Back") On 20 February, Jac attended an interview of the consultant post and was confident that she impressed the panel, but fellow registrar Sam Strachan warned her the next day that Diane appeared to be the favoured candidate. That day, Jac encountered a man named Billy whose arm had been severed in the hospital's elevator shaft. Despite her colleague's reservations, Jac was keen to reattach Billy's arm, but the attachment was later compromised, and Billy developed sepsis. Jac took responsibility for Billy's worsening condition and admitted that she was trying to impress Ric. Ric nonetheless praised Jac's tenacity and assured her that both she and Diane would make fine consultants, but Nick Jordan was ultimately given the post. (HC: "Out on a Limb")
Conflict with Nick Jordan
In March, Nick took over the treatment of Carlo Cominetti, a patient scheduled for an aortic valve replacement on Darwin presenting with a duodenal ulcer, and decided to operate on him on Darwin. Jac believed that Nick was hoping to perform cardiothoracic surgery and, as Carlo had previously undergone a laparotomy, threatened to inform Ric if he failed to properly inform Carlo of the surgery's risks. In theatre, Jac had Connie Beauchamp brought in when Nick put Carlo on bypass after he developed aortic stenosis, but Connie was impressed by Nick's adaptability and allowed him to assist on the aortic valve replacement. Jac accused Nick of setting up the situation in theatre to ingratiate himself back into cardiothoracics, but Nick threatened to expose her for lying about her level of experience with the surgery. (HC: "Let It Shine")
Nick continued to show an interest in attempting cardiothoracic procedures. While Nick was attending a cocktail party, Jac paged Joseph Byrne from Darwin to assess a patient named Philip whose condition was worsening, and Joseph found a large tear to Philip's tracheobronchial junction. Once Nick arrived in theatre, he berated Jac for not informing him of further complications to Philip's health and blamed her for the incident. The following morning, Jac explained her actions to Ric, and Ric reminded her that she needed to confer with senior colleagues from her own department and work entirely off of facts. (HC: "Snake in the Grass")
In April, Jac overheard Nick undermining Ric's clinical skills and professionalism to his patient Jenny following a failed small bowel transplant. She warned Ric about Nick attempting to "[carve] out his own niche" and urged him to consider the threat Nick posed to his career and his relationship with Diane. (HC: "Honesty") On 6 July, when Nick was vying for a cardiothoracic consultant post at St Luke's Hospital, Jac and Ric informed Lord Byrne and Connie that Nick was dismissed from St Damian's Hospital after his patient died from a swab being left inside of them. (HC: "The Truth Will Out") Despite the revelation, Nick was still offered the post and accepted it. (HC: "Extreme Measures")
Beginning of relationship with Joseph
On 24 October, while Keller was cleaned up following a major incident exercise, Darwin covered all non-elective general surgical admissions. There, Jac found Joseph Byrne unconscious in the staff room after he overdosed on fentanyl. Jac managed to reverse the effects of the drug and revive Joseph, but he insisted on no one finding out about the incident. Jac nonetheless informed his father Charles, but Charles reprimanded her for trying to "curry favour" with him and advised her to contact Joseph's superiors in future. Jac tried to apologise to Joseph, but he informed her that Elliot had barred him from operating for a week, and her intervention had not helped his relationship with his father. (HC: "Before a Fall")
In November, Jac and Joseph disagreed over the recipient of Gareth Jenkins' heart; Jac proposed fulfilling Gareth's dying wish and giving the heart to his father Arthur who needed a heart transplant, but Joseph wanted to comply with legal guidelines. Lord Byrne was supportive of Jac's idea and decided to go ahead with the transplant. After Jac convinced Joseph that their actions were morally right, the two decided to put their disagreements behind them. When Joseph mentioned that he was attending a Holby Cardiac Foundation get-together, Jac volunteered to pretend to be his girlfriend to attend the gathering and ingratiate herself with his father. (HC: "Sins of the Fathers") By December, Joseph felt that he and Jac had taken their fake relationship too far, but Jac asserted that she was not pretending and said that she wanted them to be a couple. A surprised Joseph was receptive of the idea, and the two shared a kiss. (HC: "Crossing the Line")
In January 2007, Jac learned that there was a vacancy for a general secretary position at the Surgical Association, and Lord Byrne was on the selection committee. Elliot Hope's daughter Martha warned Joseph that Jac was exploiting him because of his father's status, but Jac reassured him that their relationship was genuine, and the two had sex in an on-call room. Later, Joseph decided to withhold his application to focus on improving his surgical skills and recommended Jac to Lord Byrne. (HC: "The End of the World as We Know It")
Operation in Dubai
On 16 January, Jac discovered that Joseph was accompanying Lord Byrne and a team of surgeons to Dubai to resect a bowel tumour and urged him to take her with him, but he did not feel that it was appropriate. After failing to secure the vacant locum consultant post on Keller, Jac feigned tears and told Joseph that she felt that he did not believe in her, prompting him to reassure her and have Lord Byrne place her on the Dubai team. (HC: "Face Value")
In Dubai, Jac and Joseph were forced to lie about being consultants and operate on Mohammed — the son of the wealthy Ahmed bin Abdullah al-Hashimi — with his personal nurse Faye Morton, as Lord Byrne had contracted a virus. After discovering unforeseen complications, Jac and Joseph decided to reschedule the operation and convinced Faye not to report them for lying about their expertise. The next day, the en bloc resection went ahead, but Jac had lied about having performed the operation before. Nevertheless, Jac and Joseph managed to successfully complete the operation, and Ahmed agreed to not to inform Lord Byrne of their actions and payed them £20,000 each for saying his son's life. While en route to the airport, Joseph grew concerned about Faye when she failed to return his call; upon returning to Faye's hotel, Jac and Joseph took Faye back to England. (HC: "What Lies Beneath") Upon their return to Holby, Jac and Joseph helped Faye secure a job as a bank nurse without having to disclose details surrounding her employment in Dubai. (HC: "Into the Dark")
In March, Joseph was concerned about the "completely irrational" temperament of Bruno Jenkins — a patient of Jac's who was suffering from cancer — but Jac took issue with Joseph interfering with her work and told him that she was responsible for her own clinical decisions. At Bruno's bedside, Jac told him that she no longer considered Joseph "useful" to her career and was considering dumping him, and she admitted that she was only keeping him company to impress Lord Byrne who she saw as a "step-up". Jac later left Joseph but changed her mind when Lord Byrne expressed his pleasure at their relationship. (HC: "The Borders of Sleep") Later that month, Joseph took exception to Jac trying to upstage him in front of his father and confronted her over the appropriateness of her inviting his father out to a meal. When Faye warned Jac that, at a "weak moment", Joseph could potentially tell Lord Byrne about what transpired in Dubai, Jac apologised to Joseph and asked for his forgiveness. (HC: "Stargazer")
Seducing Lord Byrne
In April, Dr Costello of the St Raphael's Institute in Cincinnati was scheduled to lead an elective cholecystectomy at Holby City Hospital using telesurgery, with a Holby-based surgical team led by Dan Clifford on hand in the event of an emergency. Knowing that Lord Byrne was heavily involved, Jac was keen to assist, but Dan refused to allow her onto his team. While speaking to the patient, Alan Simpson, Jac learned that he had agreed to undergo telesurgery in exchange for the Cincinnati institute potentially providing treatment for his step-daughter Rosie's cancer. After Rosie was admitted onto Darwin, Alan decided to stall the surgery while waiting for her test results. When Joseph agreed with Elliot Hope's opinion that Rosie's condition was terminal, Jac disclosed the assisted suicide of Elliot's wife Gina to discredit his opinion and urged Alan to undergo the telesurgery to secure a better chance of a second opinion. Alan decided to go through with the procedure, and Lord Byrne rewarded Jac by allowing her onto the theatre team. Joseph was disgusted by Jac's conduct and believed that she villified Elliot to further her own career. At a thank-you dinner at the Wyverly Hotel, Jac managed to seduce Lord Byrne, and the two ended up sleeping together that night. (HC: "Paranoid Android")
The next day, Lord Byrne was keen to maintain a professional distance and, not wanting to hurt Joseph, suggested that he and Jac forget about their "indiscretion". (HC: "For Whom the Bell Tolls") When Lord Byrne found out that Jac and Joseph were still a couple, he accused Jac of misleading him and disinvited her from a medical conference; Jac claimed that she did not know how to tell him the truth as she cared about him. While celebrating his wife Anne-Marie's birthday, Lord Byrne told Jac that he overreacted and wanted to be with her. (HC: "After the Fall") In May, Lord Byrne agreed to put Jac's name forward for a GS consultant position at the Edinburgh Royal Infirmary, but he had her bumped off the shortlist as he doubted that she wanted to be with him; Jac reassured him and told him that she would be "worth the wait" once her relationship with Joseph was over. However, when Joseph thanked his father for blocking the move, a guilty Lord Byrne admitted that he was seeing Jac. (HC: "The Human Jungle")
On 5 December 2017, the team of new neurosurgeon and Director of Surgical Innovation John Gaskell asked Jac to assist with operating on Michael Ambrose, a man with a spindle cell tumour that was compressing his spinal cord. On the ward, Ollie confronted Jac about her decision to offload all of her procedures onto him, but she ultimately ordered him to stand down during an aortic valve replacement. Ollie challenged her, and she bluntly told him that he lacked the "mettle, the drive" and the "ability", and would never have "even the slightest chance of saving [his] pathetic excuse of a career" if he continued to oppose her.
Later, in her office, Ollie told Jac that he felt "empty" on Darwin and ordered her to acknowledge his resignation. Despite her efforts to discuss Michael's case and the potential pitfalls of Gaskell's trial, Ollie insisted that she owed him an apology and suggested that she was "terrified". Sacha later attempted to express his concerns about Gaskell's reluctance to share his research amongst the medical community, but Jac, overridden with anxiety, sat outside the Darwin theatre, where she was consoled by Fletch.
In theatre, Jac reluctantly proceeded to insert Michael's aortic graft, but she felt that she was unable to complete the procedure and walked out. In a confrontation with Gaskell, she accused him of being unethical and feeding off the uncertainty of his colleagues, but Gaskell insisted on having the likes of Henrik witness his work and urged her to help him. Upon their return, as Gaskell attempted to insert the tissue scaffold, Michael's artery of Adamkiewicz became unclipped, forcing Jac, who was on the verge of tears, to plug it with a pledget. Once the bleed stopped, Jac ran out of the room and broke down in Fletch's arms.
Following a moment of clarity, Jac decided to leave Holby and apologised to Ollie, insisting that it was his duty to remain at the hospital and become the consultant he "should be". On the stairs, she bumped into Raf and asked him to hand Hanssen her letter of resignation. However, in the basement, Jac encountered Hanssen's son Fredrik who proceeded to shoot her in the back. (HC: "Group Animal - Part One") She was soon discovered by Sacha, Hanssen, Gaskell and Essie who rushed her into the wet laboratory.
Using breathing equipment from a teaching aid and chloroform as anaesthesia, Sacha reluctantly performed a thoracotomy on her and discovered that one of her major vessels had been injured. Gaskell proposed printing an experimental patch to stop the bleed, but Sacha vehemently disagreed and insisted on waiting for more equipment to arrive. However, with Hanssen having left to confront Fredrik, Sacha eventually allowed Gaskell to insert the matrix, and Jac's pulse soon returned. Once Fredrik was neutralised by armed police, and the hospital's lifts were reinstated, Jac was taken to ITU. (HC: "Group Animal - Part Two")
As the general surgical ward at St James' Hospital was being downsized, Jac was keen to impress Ric Griffin in order to acquire a permanent position on Holby City Hospital's newly-expanded Keller Ward (HC: "Bird on a Wire") and managed to convince him to give her the registrar job there. Her ambitions grew upon learning of a consultant general surgeon vacancy, and she began to take credit for her colleague's procedures after lying about having experience performing complex operations. (HC: "I'll Be Back") Fearing that fellow registrar Diane Lloyd was more likely to be given the job due to nepotism, Jac allowed Diane to take the blame for endangering a patient's life after reattaching an unviable arm. However, Jac felt guilty and eventually took responsibility for the incident. (HC: "Out on a Limb") Her sense of empathy also extended to recognising issues in her colleagues' private lives, as she realised that Ric possessed feelings for Diane and urged him to act on them before Nick Jordan could sully their relationship. (HC: "Honesty")