Jess is Becky's older half-sister from a previous relationship between their father, Graham and her mother, Marguerite. Despite not being Bill Bertram's biological daughter, she was raised the same way as her younger half-brothers. It was Jim that tells Becky about Jess' harsh upbringing under her stepfather that made her grow up into the woman she is. When she turned 15, Marguerite died in a car crash and it was pretty hard on her. When Jess became an adult, she decided to look for her real father for recognition and not to have a relationship. Her aunt Florence, was able to provide her with Graham's name and she headed down to Oxshott, Surrey. When Jess met him, she asked Graham to do a DNA test to see if he was her real father. She starts dating Tom Webster(Becky's childhood friend) in Shopaholic & Baby when she likes what she saw in him. He and Jess have secretly married in Chile during the events of Mini Shopaholic.
Jess is tall(about 5'9) has short dark brown hair with hazel eyes. Her face is smilar to Becky's except for the tip of her nose which is a bit pointy. She has a long snake like scar on one of her legs from an accident she had when she was collecting a rock sample to add to her collection.
Shopaholic & SisterEdit
Jess makes her first appearance in the fourth novel. When Becky learned about her, she was excited and daydreamed that she would love going shopping with her, enjoy having girls night-in and help her cope with Suze not being her best friend anymore. She was disappointed when she meets Jess for the first time. It turns out she is studious, thrifty, environmentally friendly and a bit standoffish. During a shopping trip together, Jess tells Becky that she can't stand shopping and hates the sight of it. This caused her to try to find things that would interest her. Jess seemed to be interested more in helping Luke and his colleague, Gary, help win over the Arcodas Group, rather than bond with Becky. During a shopping trip at a supermarket, Jess attempted to teach her how to be thrifty after she tells her about her conversation with Luke about her spending problems. Becky selfishly tells her off that she has loads of money and should enjoy shopping with her. Jess got angry with her for acting like a spoiled brat and tells her that her behavior won't keep Luke in the marriage if she continues to behave the way she does by storing up more problems for herself. However, her passion for colleting rocks would lead to a falling out between them. Jess tells Becky what she really thought of her and vice versa. She leaves for Cumbria, while Becky faces marriage problems with Luke.
When Becky arrived in Scully, Jess didn't want anything to do with her and told her to leave her alone. She refuses and tells her that she wants to learn how to be thrifty after admitting she has marital problems with Luke. Jess refused to help and coldy tells Becky off that she knew it would happen the longer that she continued to behave the way she did by storing up more problems. She tells her that she'll have to learn to save her own marriage to Luke by herself because she can't rely on everyone to help her and Becky must admit to her own faults.
At an environmental meeting, Jess wasn't happy to see her there and wanted Becky to go back to London so the meeting to go tactfully. She was visually upset when Robin, Jim and the others liked her suggestions for more media attention and a public rally. Jess tells him that she knows how shallow Becky is and tried to get him to make her leave. Robin refused and tells her that they could use Becky's help because she's got a lot of good ideas that they need. Once alone, Jess finally tells her that she had a talk with her aunt, Florence, about her mother's flirtatious past and there were other men whom one of them were potentially her real father. She was asking Graham to do a DNA test and see if he's really her father. It was only then Becky realised that because they didn't do a DNA test and assumed, she is disheartened when she learns that they may not be related, unaware everyone overheard the conversation and are thunderstruck. Soon everyone in the meeting showed their disappointment with Jess for disowning her the way she did. Before leaving the meeting, Becky apologizes to Jess for being shallow and selfish. For the first time, she shows compassion and accepts the apology. Jess bids Becky farewell and wishes her luck in saving her marriage to Luke.
While stuck on a mountain in a middle of a stom together, they would finally reconcile. While Jess tends to Becky's sprained left ankle, she apologizes for insulting her passion of rock collecting. She didn't realize how much she hurt Jess until Jim showed her the collection during a visit to her home. Becky also realizes how similar they are to the point they'd risk their own safety just to get the things they wanted. A shocked Jess tries to deny it, but she knows it's true. However, she hides her passion for collecting rocks much better than Becky does when it comes to making purchases in unnecessary clothes and items. Jess understands what she saying and apologizes to Becky for being very rude to her during her visit in London. She should've tried to make an effort to enjoy Girls' Night In, but didn't and wanted to help Luke win over Arcodas. Jess admitted she was unnerved by Becky's spoiled behavior because of her step-father's harsh upbringing. Like her younger half-brothers, Jess had to fend for herself and learn the value of money at a young age. In turn, Becky admits she was right about her being a spoiled brat since she was one all her life. Because her parents gave her everything, they never taught Becky the value of money and fend for herself. As a result, she relied on everyone helping her out of debt. When Becky was told no for the first time by Jess, she finally realized it was time for her to grow up and be more responsible for her own actions. She asks Jess to help teach her how to be thrifty so she can save her marriage. She agrees and even admits that Becky only half to blame for the marital problems. She admits that Luke is also at fault because he was obsessed with wanting to win over Arcodas that he neglected his own wife for it. Becky gives Jess the silver Tiffany bean necklace she bought her a while back. She loves it, shows Becky her rock collection and accepts her as her sister.
Shopaholic & BabyEdit
Jess and Becky's relationship improved drastically. However, she still encourages her to take part in environmentally friendly activities. She was there with family and friends to show support for Becky during her labor. Jess and Tom begin a relationship with each other. They build Becky a shoe cupboard for her daughter, Minnie.
Jess and Tom had secretly married in Chile and are considering adopting their first child. Janice is trying to get them to have their own children before adopting. However, Becky defends Jess and Tom's choice to adopt first and tells her off to leave them alone.