Pre-2019: Deal with Graham
As Jamie's mother, Kim Tate, was set to prison around 2012, she tasked Graham Foster to look after him. However, when he was in a bad place he hired Andrea, who at the time was working as a barmaid at the pub he frequently visited, to do so for him by getting close to Jamie and report his movements back to him. However, after six months she would stop reporting back to him and they lost all contact, as Andrea had genuinely fallen for Jamie.
On Valentine's Day 2014, Jamie wasn't around and Andrea and Graham had a drink together, they ended up getting drunk and had a one night stand. They both regretted it never told Jamie. On 30th September 2014, Andrea gave birth to a daughter, who she and Jamie named Millie, but she never told him there was a possibility that she could be Graham's as Andrea always felt she knew she was Jamie's. Jamie remained gleefully unaware both of Andrea's deal with Graham and their one-night stand and the pair married.
2019-present: Arrival in Emmerdale
Andrea and Millie arrived in Emmerdale in early June 2019. She first ran into Jamie's mother, Kim, who was shocked to realise they are Jamie's wife and daughter. Kim remained hostile towards Andrea but reluctantly allowed them to move in with her at Home Farm. Kim eventually found out about the arrangement between Andrea and Graham and confronted her. Jamie was still blissfully unaware and despite Kim's belief that Andrea was after Jamie's money, Andrea insisted that the wealth was of no interest to her, she loved him. However, Andra realised that she had to be honest to Jamie and on 12th June 2019, she informed a stunned Jamie how Graham paid her to keep an eye on him whilst Kim was in prison. Andrea begged Jamie not to let this ruin what they had but Jamie felt like they had been living a lie. Jamie insisted that Andrea should've told him about it a long time ago but Andrea stated she didn't want to ruin what they had and assured him she loves him and vowed to win back his trust.
Graham attempted to bribe Andrea to leave Jamie but instead, she showed Jamie the money. Later Kim attempted to make Andrea leave by suggesting there was something between Jamie and his college, Rhona Goskirk. However, she talked to Jamie and they realised that Kim was playing games to break them up. When Andrea commented that the village had been bad for them, Jamie insisted that Kim was what had been bad so they would need to deal with her once and for all. Andrea and Jamie created an elaborate plan and roped in Rhona in to gain Kim's shares in the veterinary surgery. She initially fell for it, but realised what the two were up to via a call by Millie where they confessed to the whole thing, unaware Kim was hearing the conversation. However, Kim agreed to give Jamie her share in the practice in order to keep him in the village and eventually became more civil towards Andrea in means to make him happy.
In late August 2019, Andrea and Jamie worried when they were unable to obtain a place for Millie at Connelton Primary School. Kim suggested that Millie could go to Baswick Green Prep School but Jamie made it clear that he did not want his daughter to attend a private school. However, the following day, when Kim offered to babysit Millie so Jamie and Andrea could look at another school further away, she secretly arranged a meeting with the school's headmaster. Jamie and Andrea were upset that she went behind their back but Andrea soon realised that it was a good opportunity and as they didn't have many other options they should take it. However, Jamie insistentedthat Millie shouldn't have the type of childhood he had, but Andrea managed to convince him that he shouldn't let his own bad experiences come between Millie getting a good education and they agreed to Kim's offer.
In November 2019, Graham revealed to Kim that he could be Millie's father after a one night stand between him and Andrea back in the day, as a way to get back at Kim after she disclosed that they were in fact married in front of the entire pub. This caused Kim to turn on Andrea and threatening to tell Jamie. Despite Andrea's insistence that Millie must be Jamie's, Kim decided to do a DNA test via strands of Millie's hair to determine who Millie's father really is. However, after Andrea suffered a miscarriage on 2nd_December 2019, Kim took pity on her and threw the DNA results away without looking, stating that the truth should never be known. However, Graham could not face not knowing if she was his daughter or not and decided to conduct his own test. On Christmas Day, Graham got back the DNA results and Millie turns out to have been Jamie's all along. Despite the relief of the results, Graham's outburst caused trouble for Jamie and Andrea as Jamie was crushed about his wife's infidelity and ability to lie to him for all these years.
In January 2020, as Andrea and Jamie's marriage kept falling apart Andrea was furious with Graham who she thought had ruined her life. This caused Andrea to be one of the suspects when Graham was murdered. On the day of Graham's murder, Andrea discovered that Jamie had hired a private investigator to spy on her and in desperation asks Graham for help to dig up dirt on Kim as a precaution. However, Jamie realised he was wrong in spying on his wife and apologised to her. They took walk sorting out their issues but when Graham came across them, he revealed what Andrea had been up to, making Jamie furious at them both. Andrea tried to rip the papers and apologise but Jamie was having none of it. Andrea was furious with Graham and went out driving in the night. She felt awful when she accidentally ran over the Sharmas' dog Tip.
In February 2020, Andrea decided to get her own place for her and village but after Kim ruined her plans, she furiously vowed to win custody of Millie and move far away so Kim and Jamie would never see her again. In March, Andrea met a man who said he would help him get evidence against Kim that she could use in court to get Millie. They put up a camera and filmed Kim confessing to planning to kill Graham but what Andrea did not know was that the camera was still on when the two of them kissed and the man was actually working for Kim. Kim wanted to use it against her but Andrea told Jamie everything and he turned on Kim. Andrea and Jamie decided to try again. However, on 29th April, Andrea was devastated when she was Jamie kissing his co-worker Belle Dingle and realised they were having an affair. Even though she was heartbroken she decided to fight for Jamie back and didn't tell him she knew.
"Sorry?" - first line, to Kim Tate.
"Come on Jamie, you're the best stripper around." - to Jamie Tate.