Lachlan debuted on-screen on 19 March 1997. His initial scenes depict him taking his new position at the hospital where an established doctor,
Kelly Watson (Katrina Hobbs), takes a dislike to him because he is considered more experienced, despite them being equally qualified. Grieve told Helen Childs from
Inside Soap that Lachlan is completely different from Sam. He enjoyed playing a doctor because of the "amazing" experiences it created. The actor had to research the profession before taking the part. He also told Childs that "we have a medical advisor on the show who helps with the medical scenes, and she also arranged for me to go to
St Vincent's hospital in Sydney to observe some operations." He is characterised as a sweet, gentle,
tall, dark and handsome man. Lachlan begins a relationship with
Shannon Reed (
Isla Fisher), which begins soon after they meet. Grieve has said that filming the scenes with Fisher was never romantic. Their relationship ultimately fails. Shannon had previously questioned her sexuality after involvement with
Mandy Thomas (
Rachael Blake) and when she returns, Shannon decides to leave Lachlan because her feelings return. Shannon decides to begin a new life in Paris and this leaves Lachlan "heartbroken". Lachlan sleeps with
Chloe Richards (
Kristy Wright) and she becomes pregnant. Lachlan forgot about his tryst with Chloe, but she knows that the baby is Lachlan's and she decides to tell him. Grieve told Steven Murphy from
Inside Soap that "when he finds out about Chloe's secret he is totally shocked and confused, which is only natural." But he believed that there was still an obvious attraction between Lachlan and Chloe and slowly, everything begins to piece together. They decide to support each other through the scenario but end up falling in love with each other. Working with Wright presented logistical challenges during filming due to their difference in height. Grieve was above six foot in height and when the pair filmed together he had to lean on objects or sit on couches. Wright later revealed that she and Grieve attempted to make Lachlan and Chloe's "love story" unique. She added that the duo "have fun together and aren't too soppy. They wind each other up in a good-natured way, just like I and Richard do in real life." Lachlan is diagnosed with a brain tumour and has to have life-saving surgery. Lachlan and Chloe love each other and just welcomed their first child. Wright told ''Inside Soap's'' Murphy that Chloe's new life with Lachlan appears to be over. She found the scenes in which Chloe stays by Lachlan's bedside emotional and difficult to portray because Grieve was a close friend. Lachlan leaves an upset Chloe and Summer Bay behind to have possible life-saving treatment in the US. In his final episodes, Chloe tracks Lachlan down to a US hospital where he is attempting to recover from his brain tumour. Producers had invested time to develop Lachlan and Chloe's relationship, so they decided to replace the character and continue the storyline. Michael Piccirilli was cast as Lachlan's brother
James - a fellow doctor. Piccirilli told ''Inside Soap's'' Herbison that "the purpose of my character was to come in and marry the girl who was having my brother's baby." Chloe discovers that Lachlan married another woman and she decides to be with James. ==Storylines==