<P> Registrar Greg Douglas (Edward MacLiam) shirks his responsibilities by excessively delegating to Oliver; to his dismay, Connie appoints him as Oliver's mentor . Oliver pushes himself too far in an attempt to impress Greg, which earns the senior doctor a reprimand for leaving him unsupervised . Oliver tries to earn back Greg's respect, but panics while attempting to insert a chest drain, and has to be rescued by ward sister Frieda Petrenko (Olga Fedori). He invites her for a drink as thanks, but when Penny discovers that Frieda has romantic feelings for him, Oliver cancels as he does not reciprocate them . Oliver's confidence is further damaged when he mishandles a case, which results in a mother leaving her son to die alone . He moves back to the AAU, where he is shaken by an encounter with the boy's mother, which causes him to panic and embarrass himself in theatre . Penny's career begins to improve, and Oliver resents her when she is given registrar duties for a shift . Having realised that he is close to failing his F2 year, Oliver implicates Penny in a serious surgical error of his own doing, but is caught by registrar Antoine Malick (Jimmy Akingbola). </P> <P> When a patient unexpectedly dies in his care, Oliver breaks down . He confesses to Penny that he cheated in medical school by swapping one of their exam papers, so he passed on her merit while she was forced to repeat a year . Furious, Penny tells Oliver that he must confess to Director of Surgery Henrik Hanssen (Guy Henry). He writes a letter of resignation, but deletes it after a positive day working alongside Frieda, who encourages him to repeat his F2 year . After giving Oliver a final chance to confess, Penny is called away to the site of a train crash . Oliver is left alone on AAU, where he successfully performs a difficult procedure . Hopeful that Penny will forgive him, Oliver is devastated to learn that she has been killed in an accident at the crash site . Unable to cope in the aftermath of her death, Oliver turns to drugs and alcohol . He sends Hanssen a letter of resignation, which includes a full confession . His father Tony (Simon Shepherd) offers him money to choose a new career, and claims that Oliver always had more potential than Penny . This angers Oliver, who endangers his own life to save a patient and feels reinvigorated . Hanssen is impressed by Oliver's patient treatment, and overlooks his cheating to allow him a fresh start . </P> <P> Oliver continues and succeeds in his second F2 year under Elliot, who is his mentor . He begins a relationship with F1 Tara Lo (Jing Lusi). He learns she has a brain tumor and becomes fixated on finding a cure . She learns to accept it . Oliver begins spending more time at Tara's flat and later moves in . Oliver and Tara marry the day before she has a major operation . Oliver and Tara prepare for her operation, but there are complications in surgery and she dies . </P> <P> Anderson returns as Oliver in the episode "I Will Honour Christmas in My Heart" - Series 17, Episode 11, for just one episode . He makes a full return from Series 17, Episode 30 and onwards, as the new registrar on Darwin . </P>

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