At some point after September 1998, John met and married Fiona and raised her daughter as his own. Although, the relationship didn't last and Fiona moved to Australia - taking Emma with her. Not long after, Emma returned to Weatherfield as she missed her father too much. After returning to the area, Emma moved into her own flat with a friend and kept in regular contact with John. He later remarried but, once again, the relationship soured and his wife left him in 2018.
In August 2019, John was diagnosed with stomach cancer - which had become terminal by the time that it was discovered as he had delayed routine check-ups due to his hatred of hospitals. However, John attempted to protect Emma from the truth by pretending that he was simply suffering from stomach ulcers. In order to rally support around her father in his time of need, Emma attempted to persuade Fiona to return to Weatherfield from her home in Australia - to no avail.
On 12th August, Emma visited her father alongside Audrey Roberts and she was left shocked when he confessed that he wasn't really her father. Audrey attempted to convince Emma that her father had been high on medication and didn't know what he was saying, but Fiona later confirmed over the phone that John had been telling the truth. When Audrey realised that Fiona was Emma's mother she began to suspect that Steve McDonald was her true father and shared her suspicions with Steve's mother Liz.