Introduction and characterisation Jason was introduced as the nephew of
Serena Campbell (
Catherine Russell). After Serena learned that her long-lost sister was dead, she emailed Jason asking to meet him and he turned up at Holby during Serena's shift. Russell explained that Serena was only expecting a reply, but because of his Asperger syndrome he takes the message literally and shows up. Following his introduction Robertson received praise from viewers via the social networking website
Twitter. He attributed this to his character's one liners stating, "the reaction has been really good, really positive. I get the best lines as well." Robertson described Jason as "really nice and sensitive with a deadpan sense of humour and a genuine desire to do good". He also thinks that Jason lacks self-confidence. Jason later takes employment as a porter at the hospital. Jason takes three months off work to recover from his injuries. Elinor's death effects Jason and he visits a
grief counsellor. When Jason and registrar
Xavier Duval (Marcus Griffiths) witness Sian Evans (Ajjaz Awad) thrown from a vehicle in the hospital car park, they go to help and discover a stab wound.
Relationship with Greta Allinson Producers introduced a love interest for the character in 2018, Greta Allinson (Zoe Croft). She is admitted to AAU where Serena treats her. Greta tells Serena she cannot treat her because she is Jason's aunt. Serena interferes again when she presumes that Jason and Greta will move in with her following the babies birth. When Bernie returns from working in Nairobi, she asks Serena why she stayed on at the hospital. A
Holby City publicist the told Tyler from
Inside Soap that it was because "her nephew Jason and his other half Greta are due to have a baby - and heavily rely on Serena, of course!" Greta later gives birth to a baby girl named Guinevere and a patient makes Jason worried about what would happen to his partner and daughter if he was to die. Harper teased the wedding during November 2018 and revealed that they had hired musician and priest
Richard Coles to play Henry de Havilland, who would officiate the on-screen ceremony. Jason and Greta's service was due to be conducted by
chaplain Lexy Morrell (Jenny Howe) who was impaled by a shard of glass when a church roof collapses. Jason enlists Xavier's help to ensure the wedding still goes ahead. Xavier gets the hospital gardens ready and organises the ceremony there. Jason's colleagues
Dominic Copeland (
David Ames) and
Lofty Chiltern (
Lee Mead) also join the celebrations for a double ceremony. Harper branded it a "joyous episode celebrating love and commitment in all their diverse forms." On his first day back to work following Greta's accident, Jason is unable to cope. Serena suggests he put on earphones to keep him calm. When consultant
Ange Godard (
Dawn Steele) notices this she is rude to him not realising he has Asperger syndrome. ==Reception==