Joseph Charles Mortimer Byrne is a former cardiothoracic surgical registrar, at Holby City Hospital.
Time at Holby City Hospital
Joseph arrives at Holby City Hospital in episode "Mother Love", when he and fellow cardiothoracic surgeon Sam Strachan vie for a registrar position. Although Consultant Connie Beauchamp initially intends to hire Sam, she is persuaded by Joseph's father, Lord Byrne, to create a second position for Joseph. He joins Connie's firm, but soon switches to work under the ward's second Consultant, Elliot Hope. The two become close, as Joseph becomes involved in Elliot's troubled family life. In turn, Joseph begins to confide in Elliot, and reveals that his brother Harry is in a coma as a result of a failed suicide attempt. Joseph discloses his guilt about the incident, and explains that he knew his brother was worried about exams, but ignored a telephone call from him on the evening he took an insulin overdose. As a result, he can no longer bear to hear a phone left ringing, and has developed OCD.
To cover up the symptoms of his disorder, Joseph resorts to stealing pharmacy drug Fentanyl and self-administering it before operations. In the episode "Before A Fall" he overdoses on the drug, but is saved by his colleague Jac Naylor. Shortly thereafter, they become a couple, although Joseph is unaware that Jac is only interested in him because of his father's influence. Jac manipulates Joseph into having his father add her to a surgical team flying out to Dubai to perform pioneering surgery. When things go awry there, she convinces Joseph to lie about their qualifications so that they can perform the operation themselves, which endangers both their careers, and results in their lives being threatened by the patient's influential father. In the episode "Paranoid Android" Jac begins cheating on Joseph with his own father, for a period of several months, until Lord Byrne calls an end to the deception and confesses their infidelity to his son.
Joseph quickly comes to loathe Jac, not only for cheating on him, but for breaking up his parents' marriage. Before Lord Byrne is able to secure the promotion Jac wanted from him, he dies from complications arising from a perforated stomach ulcer. When Jac attends his funeral in the episode "Bad Reputation", a furious Joseph slaps her and leaves her badly bruised. Jac continues to torment Joseph for several weeks, and flaunts the fact she inherited a ring in Lord Byrne's will that had once been promised to Joseph by his grandmother. His friend and colleague Faye Morton takes it upon herself to steal the ring, and returns it to Joseph to do with as he sees fit, in the hopes that this will allow him to move on.
Early in series ten, Joseph's brother's condition deteriorates and he is admitted to Holby City Hospital in need of an operation. Faye supports Joseph, and the two kiss. Joseph's hopes are raised when his brother opens his eyes, and he considers expensive neurology treatment in America to try and rouse Harry from his coma. Shortly thereafter, however, Harry's condition worsens again, and Joseph and his mother allow Harry to die. Following his brother's death, Joseph returns to work to find Jac on trial for Sam's old position. This reignites their feud, and Joseph is unable to block Jac from gaining the position. His relationship with Faye develops slowly, however Joseph's suspicions are raised when she lies to him about her whereabouts on several occasions, leading to the eventual discovery that the police suspect her of the murder of her second husband, Donald. An exhumation reveals that Donald did not die of cancer, as Faye insisted, but of arsenic poisoning. Joseph remains suspicious, but supports Faye as their relationship continues to develop. When Faye has a pregnancy scare, he proposes to her, and insists that he meant it even after the discovery she is not actually pregnant. Joseph is devastated when Faye appears to have stolen £5,000 from him and left the country, but discovers she is in fact in trouble in South Africa. After flying out with colleague Linden Cullen, Faye reveals she has a ten-year-old son, Archie, who lives in a care home because of a genetic disease. Joseph saves Archie's life in a risky operation, and he and Faye return from South Africa engaged once more, much to Jac's chagrin.
Despite subsequent setbacks in their relationship, such as Jac briefly deceiving Joseph into believing that she is pregnant with his child, Faye and Joseph marry. On the day of the ceremony, Linden confesses to Faye that he is in love with her, and they kiss. She instantly regrets it, however, and tells him that she loves Joseph. When Archie's nurse Lauren later accidentally administers him the wrong drug, he dies. Faye and Joseph grow apart in the aftermath and she develops romantic feelings for Linden. She and Joseph separate, but after she begins a relationship with Linden, she discovers that she is pregnant with Joseph's baby. Increasingly concerned that Faye may be a pathological liar, Linden terminates their relationship. Faye is later attacked by a heroin-addicted patient, and when Linden attempts to defend her, he is hit in the head with a glass bottle and dies. Faye suffers a breakdown in the aftermath, and is admitted to a psychiatric unit. She self-harms, and refuses to leave the unit when she goes into labour, until Jac assures her that Joseph does not intend to take their child away from her. Faye delivers a boy by Caesarean. She initially fails to bond with him, but when Joseph puts their divorce proceedings on hold, she makes an effort and names him Harry, after Joseph's deceased brother. Despite Joseph's opposition, she insists on returning to the psychiatric unit. Jac's support during this time results in a renewal of their relationship, and when Faye secretly makes plans to leave the country with Harry, Jac helps convince her to leave the baby with Joseph. Joseph struggles as a working father, and accepts a job as a GP in Penrith. Jac declines his offer to accompany him, so he departs with Harry, leaving her in tears.