Nell Fairfax is a young woman Jai Sharma met at a Narcotics Anonymous meeting in the village hall in late March 2017. Jai talked about his late girlfriend Holly Barton and how he blamed himself for her death. When Nell told the group her story, Jai drew parallels between Nell and Holly.
After the meeting, Nell approached Jai and thanked him for being encouraging. Jai noticed Nell shivering so offered her his coat. Nell told Jai that Holly would be proud of him. Later, Jai found his coat at the village hall but noticed his wallet was missing. He went chasing after Nell who denied stealing the wallet, but handed it over after Jai threatened to call the police. Jai took Nell for lunch at The Woolpack and they talked. Nell thanked Jai for the meal and for not calling the police. Nell managed to track Jai down the following day. She hoped he'd give her money but Jai refused as he wasn't able to trust her.
A few weeks later, Nell had an overdose and reached out to Jai. Jai collected Nell from the hospital and allowed her to stay at Holdgate Farm, although Jai's sister Priya wasn't happy with Nell around her young daughter Amba, so Nell left. Jai brought Nell back and offered her a job at his factory and to pay for her to stay at the B&B for a few weeks. Nell accepted Jai's offer after he explained he wanted to help like he couldn't with Holly.
After Jai's ex-wife Megan Macey accidentally left baby Eliza in her car while she rushed off to a meeting, Nell spotted Eliza and took her up to the factory. Megan was fuming at Nell, but Jai wanted to talk things out. At the park, they had a heart to heart and Jai asked Nell why she felt compelled to intervene with Eliza. Nell revealed her baby daughter Rosie was taken away from her due to her heroin addiction and that she was worried the same thing would happen to Eliza if social services got involved.
Jai and Nell then started to begin a relationship, clandestinely at first, because of everyone's imminent disapproval and Megan's ban on Jai seeing Nell. Everyone soon found out, and after an argument, Megan finally agreed that Jai should see who he wants. After wanting to take things slow and asking her to move out, Jai found Nell slitting her wrists and let her stay in his spare room.
After this incident, Jai asks Nell to stay with her at Holdgate Farm and their relationship remains public. Nell overhears half a conversation between Moira and Jai where Jai says that Nell has "baggage" but that he is falling in love with her. Nell goes hysterical and tries to walk out on Jai. When Jai explains the whole conversation, they reconcile.
Jai went out to a department store to buy a ring to propose to, but on one of the shelves, Jai notices a photo frame for sale with a picture of a baby looking exactly like the photo of Nell's daughter Rosie. Jai goes to the graveyard where "Rosie"'s funeral took place, but discovered that the baby wasn't Nell's. When going home to look through her stuff, Jai finds newspaper clippings of Jai's ex-girlfriend Holly Barton who had died from a heroin overdose in 2016. He also finds a book titled "An Evening with Rosie" and a leaflet on addiction & recovery among the newspaper clippings. When confronting Nell over this, she admits to this and when she goes to hug Jai he pushes her and she hits her head on the table. Jai's dad Rishi and ex-wife Megan Macey walk in and hear their conversation, exposing Nell as a psychopathic con-woman. Nell briefly manages to trick Holly's mother Moira into believing that she miscarried and that Jai was violent with her upon finding out. However, when the truth is revealed, Moira violently throws Nell out, calling her a bitch. Nell admits to Jai she was wrong, and asks him to drop her off at her mum's house. He concedes, and they part ways as she approaches the front door of the house. The woman who opens the door, who lost her child to drugs, identifies Nell as a woman on a telephone who needs help. It quickly becomes apparent that Nell lied to Jai, as she tells the woman her name is Holly.
Any information about her life that Nell gave out is unreliable, since she was conning Jai all along. Therefore, her origins are uncertain.