On 7 February 2013, it was announced that the four-strong Willis family would be introduced to Neighbours, as part of an ongoing overhaul of the show's cast and renewed focus on family units. News of the Willis family's introduction came shortly after producers decided to also bring in the five-strong Turner family. Executive producer Richard Jasek commented "As viewers will find out shortly, the Turners are a family of secrets, and the unique backstory of the Willis family is just as compelling." The character of Brad Willis (Kip Gamblin) was reintroduced to the show, along with his wife Terese and their teenage twins; Josh (Harley Bonner) and Imogen (Ariel Kaplan).
Actress Rebekah Elmaloglou was cast in the role of Terese, the matriarch of the Willis family. Elmaloglou's agent asked her to audition for the role in late 2012 and she thought appearing in Neighbours would be something "interesting to do", especially as she had previously appeared in rival soap opera Home and Away. Elmaloglou won the role and she and her family relocated to Melbourne where the Neighbours studios are based. The actress thought it was an exciting time to join the show and did not feel under any pressure. She also said the production style was similar to Home and Away, but Neighbours was fast paced because they shoot an extra episode a week.
Before she began filming, Elmaloglou asked the producers to change the pronunciation of her character's name. Elmaloglou was initially happy with her character's name, as it was a deviation of her mother's name, Theresa. However, she was concerned about the pronunciation chosen by the producers, explaining "At first I thought, 'That's nice, I'll always have mum close to me' - until I realised it's pronounced exactly how mum hates it! I knew she would cringe every time she watched me on Neighbours." The producers agreed to change the pronunciation shortly before Terese was mentioned on-screen. Elmaloglou started filming her scenes two weeks after the casting announcement. Elmaloglou made her first screen appearance as Terese on 14 May 2013.
Elmaloglou described Terese as being "ambitious, organised and extremely capable when it comes to her job". She thought her character would appear to be "a tough nut", but she displays a softer side when it comes to her family. Elmaloglou liked that Terese's personality was changeable as it made her interesting. She did not think Terese had a devious side, but she often riled people when she made decisions on their behalf. A writer for the show's official website called Terese "a devoted wife, loving mother and hard working career woman." They also agreed that she was ambitious and had put in the hard work to achieve her dreams.
Elmaloglou said "Terese is a good mum, but she's also very career-orientated too. I think Terese worries about it a little bit more than she should." Elmaloglou thought Terese was the kind of person she would be friends with, branding her an "all-rounder". She explained that she admires Terese and is quite similar to her in terms of how organised they both were. However, Elmaloglou thought Terese was more businesslike than her and she was unsure if she could be the mother of three children. She later commented that she and Terese did not really have anything in common and that she was much naughtier than Terese was.
Terese married Brad Willis (Gamblin) when she was 21. They have three children; twins Josh and Imogen, and Piper. Gamblin explained that Brad and Terese met and married very quickly. Terese has some issues with Brad's former wife Beth (Natalie Imbruglia) because of their history and Gamblin called the situation "a bit messy". Gamblin added that Brad and Terese's marriage was pretty strong. Elmaloglou agreed, calling the marriage "absolutely solid" and saying that although Brad and Terese are different, they work well together. Prior to relocating to Erinsborough, Terese had become the breadwinner and was running the family, as Brad was busy coaching Josh, who was a competitive swimmer. Shortly after her arrival, Terese was introduced to Brad's ex-girlfriend Lauren (Kate Kendall). Elmaloglou explained that Terese was aware of Brad's past and she was fairly relaxed about it. As Terese felt secure in her marriage, she got on well with Lauren and their respective husbands became rivals instead.
Elmaloglou was initially shocked that she was cast as the mother of three teenagers and told a New Idea writer that she liked to think Terese was a very young mother. After Imogen was diagnosed with an eating disorder, Elmaloglou said Terese and Brad would feel guilty for not noticing, as they had been too focused on Josh and his swimming. The actress said the situation wakes them up and makes them realise that they had been neglecting their daughter. Elmaloglou commented "There is an element of regret that they weren't more in tune with Imogen and her problems." Imogen found it hard to accept that her parents knew about her condition and their reaction was just added pressure. In an effort to help Imogen, Terese opened up to her about her own eating disorder she had suffered with as a teenager. Kaplan called the moment "really powerful" and thought it would bring Imogen and Terese closer together, as well as help Imogen to come to terms with her own condition.
Elmaloglou hoped that Brad and Terese's youngest daughter, Piper, would be introduced at some point, especially after the character's began talking about her more during storylines. Elmaloglou thought Piper's introduction would add another dynamic to the family because of her young age. In early 2014, Lauren told Brad that she had given birth to his daughter twenty years ago. Lauren had believed that their daughter died soon after birth, but she had actually been adopted out. Terese did not take the revelation well and Elmaloglou said it was definitely a shock and not something she had ever prepared for. She explained that Terese had been fine with the fact that Lauren and Brad had dated, but she struggled with the new situation and she worried about her own family and how the news would affect them. When asked what advice she would give Terese, Elmaloglou replied "My advice to Terese would be to think before reacting and while it's a huge ask, try to put herself in Lauren's shoes... And watch Lauren like a hawk!"
In April 2014, Terence Donovan returned to Neighbours as Doug Willis, Brad's father. Donovan had previously played Elmaloglou's on-screen father in Home and Away. The actress was pleased to be reunited with Donovan "as father and daughter-in-law after all these years." On-screen, Terese expressed her fears that Doug preferred Brad's ex-wife Beth to her. As Doug was "old school", he was not keen on Terese balancing her career and family. He was also not used to Terese's feisty side. Elmaloglou thought Terese was being a little paranoid and said the fact was Doug and his wife, Pam (Sue Jones), had spent more time with Beth. During Doug's visit, Terese was "bemused" when she found the television remote in the fridge and assumed Doug was getting a little forgetful due to his old age. Doug continued to have memory lapses, but Brad refused to listen to Terese's assumptions that it might be more serious, insisting that Doug was fine. However, Doug was later diagnosed with Alzheimer's disease. Elmaloglou added that the diagnosis would affect the family and she hoped Donovan and Jones would return to explore the storyline further, as it is a common disease.
Terese was introduced as the new manager of Lassiter's Hotel, which is owned by Paul Robinson (Stefan Dennis). Terese decided to visit Erinsborough alone to check out the hotel and meet with Paul. Elmaloglou told an Inside Soap reporter, "This is the perfect chance for Terese to see things at the hotel as they really are, before Paul can cover anything up!" Paul believed he was conducting an interview for the manager's job, so he was surprised when Terese let slip that his sister, Lucy (Melissa Bell), had already offered her the job without consulting him. Elmaloglou said Terese was keen to get on with things and it would not take her long to get the measure of Paul. Elmaloglou said Terese and Paul were "fantastic foils for each other" and believed Terese was capable of holding her own with Paul. Dennis pointed out that Terese and Paul shared a love/hate relationship and said Paul respected Terese for her business skills and the way she stands up to him. He added that while there was a tension between them, they did work well together.
In January 2014, Terese and Paul's working relationship became very strained when Paul tried to make things intolerable for Terese at Lassiter's. Dennis told John Burfitt from TV Soap that Paul wanted to make Terese as uncomfortable as possible in order to get rid of her from the hotel. He explained "I actually don't think he genuinely dislikes her, but he has decided to dislike her as he had no control in her being there and being such a control freak, he didn't like Lucy coming in and telling him who was going to work there. He then decided to buck back against the decision and push her out in every way he can." After Paul pushed Terese too far, she quit her job with immediate effect. Lucy was "furious" as she was aware that Terese was a great employee and she threatened to remove the hotel from the Lassiter's chain to make Paul see sense. Neither Elmaloglou or Dennis thought Terese and Paul would have an affair in the immediate future. Elmaloglou doubted it would happen as Terese's marriage to Brad was very solid. She did think with all the tension between Terese and Paul, there could be an underlying attraction there though.
When Brad and Terese experienced difficulties in their marriage, Terese walked out on Brad and moved into Lassiter's. Elmaloglou enjoyed working on the storyline, but she also found it hard as she loved that Brad and Terese had such a solid marriage. The storyline also gave her a chance to explore Terese's many levels and said that "a different side of her" would emerge. Elmaloglou explained that Terese did not think her marriage was over, but she had realised that instead of blaming her problems on other people, she needed to work out what had gone wrong within the marriage and her relationship with Brad. She continued, "Terese is not moving out because of a final decision over her marriage, it's just that the last six to twelve months have been so overwhelming and she needs space. Who knows whether moving into Lassiters is really a good idea, but it's just a way for her to take some time out of the Ramsay Street situation." While Terese was staying in the hotel, Paul invited her former boss, Ezra Hanley (Steve Nation), to Erinsborough. Terese had previously admitted to having feelings for Ezra. Elmaloglou said viewers would be questioning why Paul would bring Ezra and thought the most likely reason was that he did not like Brad.
The actress was concerned that some people would think that Terese was trying to get payback on Brad by spending time with Ezra, but she said that Terese was just confused and placed in "a very vulnerable situation". Elmaloglou added "There's so much going on at home, so Terese falls into a trap and gets caught up in a situation. It was challenging to film, but it was something a little bit different, which I liked." When Ezra later asked Terese to dinner, she accepted following another argument with Brad, who suggested that they make their split more permanent. Dennis said Paul was pleased with the development as he wanted Terese to have some fun and be with someone more "intellectually matched with her". After dinner, Ezra suggested that he and Terese should go to her room to continue working on plans for the Erinsborough Festival. Tereese "ignored her fears" and agreed. However, she regretted her decision when Ezra made advances towards her and chose not to accept her refusal.
Terese was "furious" with Paul for bringing Ezra back into her life and for telling Brad that she had spent the night with him. When she told Paul that Ezra had tried to attack her, Paul felt guilty and Dennis said he was "genuinely concerned" about Terese. Brad later found Terese and admitted that he still loved her, causing her to break down in his arms and confess what had happened with Ezra. After Ezra was dismissed from his job, he tried to sue Paul and Terese. When Terese suggested that they give him a settlement, Paul assures her that he has another idea to get rid of him. Shortly afterwards, Terese found Ezra badly beaten and unconscious. During the police investigation, Terese was found to be physically incapable of committing the crime, while Paul had an alibi. The police then suggested that either Josh or Brad could be responsible, with Brad having recently had a hand injury treated. However, it soon emerged that Paul had hired Gary Canning (Damien Richardson) to assault Ezra.
In May 2015, Ezra returned to Erinsborough as the acquisitions manager for Lassiter's following its sale to another hotel chain. Elmaloglou told All About Soap's Claire Crick that Terese was initially worried about her job after the sale, but Paul assured her she would be okay. After she started to relax, Terese was "mortified" to discover that Ezra was in charge. Elmaloglou explained, "She tries to be grown-up about it, but he makes her life miserable. She hasn't forgotten what happened when he was last in Erinsborough." Terese later quit her job after she could not take it anymore. Elmaloglou stated that Brad was behind Terese's decision and suggested that she should take a break and go to Canada to see their youngest daughter Piper. The actress commented that Terese was worried about leaving Brad behind with Lauren, but she just had to have faith in them. Elmaloglou added that she hoped Terese would get her job back, so she could continue to work with Paul.
As Terese worried about her job, her children's problems and Brad's closeness with Lauren, following the death of her husband, she turned to alcohol to cope. She began drinking more at lunch and after work, but tried to cover it up, as she did not want to risk losing her job. However, Sheila Canning (Colette Mann) soon noticed some of the stock at The Waterhole was being stolen and set up CCTV on the storeroom, where Terese was caught helping herself. Shelia confronted Terese, who tried to dismiss her concerns. Sheila then went through the Willis' bins for evidence and found a bottle from The Waterhole's stock. A fearful Terese told Sheila off for questioning her integrity, but a Waterhole employee later commented on Terese's drinking and Sheila asked her whether she had a problem with alcohol. In a bid to prove she did not have a drinking problem, Terese agreed to Brad's suggestion that they take part in the "Alcohol-free August" campaign. But when Terese spent time with Paul, she enjoyed a bottle of wine, causing more strain on her marriage.
While attending an AA meeting, Terese meets Walter Mitchell (Greg Stone) and has an instant connection with him. Sonya warns Terese that Walter's intentions might not be honourable, but Terese arranges a date with him, which ends in a kiss between them. Elmaloglou commented, "Walter is attractive and funny, and a nice diversion from all the stuff Terese has had to go through." When Paul went on trial for causing an explosion at Lassiter's, which contributed to the deaths of Doug and Josh, Terese committed perjury in a bid to see him jailed. After her lies were revealed, Terese struggled to cope and began drinking again. Following her arrest for perverting the course of justice, Terese drank until she passed out. Piper then found her collapsed in the laundry room.
After accepting the Lassiter's Erinsborough general manager's job, Terese meets with the hotel's owner Paul Robinson for a tour. Paul is initially unaware that she has the job and Terese allows him to interview her, before telling him that she just wanted to make sure they would work well together. Terese moves into Number 22 Ramsay Street with her husband Brad and their twins Imogen and Josh. She learns that Brad's ex-girlfriend, Lauren Turner, is living across the street and befriends her. Terese fires receptionist Caroline Perkins (Alinta Chidzey) for being lazy and rude. Caroline then sues the hotel, claiming that Paul sexually harassed her. Terese arranges for Caroline to be paid off. After Terese stays late at work, Brad accuses Paul of trying to take advantage of her in front of the inspector, costing the hotel its five star rating. Terese assures Brad that he got it wrong. Susan Kennedy (Jackie Woodburne) becomes concerned that Imogen might have an eating disorder, but Terese does not believe her. Imogen later collapses and is admitted to hospital with a torn oesophagus, as a result of bulimia. Terese tries to get Imogen to talk to her, admitting that she once suffered an eating disorder too. After Imogen breaks down in her arms, Terese finds her a counsellor.
Paul promotes Terese to Head of Operations for the Lassiter's complex. He installs paid parking for the complex, angering the business owners. Terese realises Paul set her up, so she increases the maintenance rates for the apartment tenants and scraps the paid parking. Relations between Paul and Terese deteriorate and she quits her job. Paul threatens to sue her for breach of contract, but Terese counter-sues him for defamation. Lucy convinces Paul to reinstate Terese. When Josh is badly injured in an abseiling accident, Brad blames Mason Turner (Taylor Glockner) and sues him, causing tension between the Willis and Turner families. Terese tries to persuade Mason to leave Erinsborough for a job in Darwin and Lauren accuses her of wanting to get rid of her son. Terese struggles to cope when Lauren informs Brad that they have a daughter together, who was adopted out. The Turner and Willis families agree to hire a private investigator. However, a false lead causes Lauren to call off the search. When Brad's father, Doug, visits, Terese believes that he prefers Brad's first wife, Beth, to her, but they rebuild their relationship when Doug is diagnosed with Alzheimer's disease. Brad's mother, Pam, soon arrives in Erinsborough and Terese helps her see that Doug needs her support.
Terese begins seeing Imogen's counsellor as a way of coping with all the stress in her life. She also learns that Brad has hired a new private investigator to find his daughter and she urges him to tell Lauren. Brad and Lauren get a lead and fly to Adelaide. Brad stays longer than planned, causing further estrangement from Terese. When he returns, Terese questions the strength of their marriage but they reconcile. After Brad loses his job, Terese pushes him to take a teaching position at Erinsborough High. She also tries to help Paul when he becomes depressed, and clashes with hotel guest Paige Novak (Olympia Valance). Paige is revealed to be Lauren and Brad's long lost daughter and Terese struggles to accept her. Upon learning Paige trashed Harold's Store, Terese has her arrested. She tries to convince Lauren's husband Matt (Josef Brown) to join her in keeping an eye on Paige, but he refuses. Terese later drops the charges and decides to give Paige the benefit of the doubt. When Terese learns that Brad kissed Lauren in Adelaide, she orders Brad to stay away from Lauren, suspecting a continuing affair. Terese and Brad's marriage becomes strained, and Terese moves into the hotel.
Terese confides in Paul about how she fell for her previous boss Ezra Hanley, and Paul invites Ezra to Erinsborough to help her organise a festival. Terese and Ezra almost kiss, but Terese pulls away, realising she loves Brad. She asks Ezra to leave her room, but he refuses and Terese has to physically force him to go. Brad asks Terese to work on their marriage and she agrees. Ezra attempts to sue Terese and Paul, but he soon leaves after he is attacked by a mystery assailant. Terese is reunited with her brother Nick (Damien Fotiou) when he comes to Erinsborough to take up a job at the hospital. She learns that the day before her wedding to Brad, Nick engineered a meeting between Brad and his ex-wife, to see if Brad was faithful to her. She tries to calm things between Brad and Nick as they feud. Terese stumbles upon Matt kissing Sharon Canning (Natasha Herbert) and pulls him out of Sharon's room, telling him to go home to Lauren. After Matt dies, Terese tries to keep Sharon from talking to Lauren and sends her on a cruise. She starts to worry about Brad and Lauren's closeness. It soon emerges that Nick has been treating Paul for leukaemia that he does not have and attempts to flee Erinsborough, but Brad calls the police and he is arrested.
Ezra returns as the acquisitions manager for the Quill Group who purchase Lassiter's. He reduces Terese's responsibilities and make things difficult for her. After he makes a suggestive comment, Terese quits her job and goes to Canada to see Piper. Upon her return, Terese learns from Ezra's son Clem (Max Whitelaw) that his ex-girlfriend accused Ezra of assaulting her. Terese contacts Chloe Jones (Gaby Seow) and encourages her to go to the police, which results in Ezra's arrest. The Quill Group hire Terese as the manager of Lassiter's. After learning Brad and Lauren spent an evening together, she accepts that nothing happened between them, but warns Brad that their marriage will be over if he lies to her again. Still feeling insecure in her marriage, Terese pushes Lauren and Robin Dawal (Max Brown) together. Terese realises Paige is trying to reunite Brad and Lauren, so she encourages Paige's adoptive mother Mary (Gina Liano) to reconcile with her daughter and take her to Singapore. Terese tells Brad about Paige's plan and he gets her to apologise to Terese. Sheila Canning catches Terese stealing wine and believes she has a problem with alcohol. Terese dismisses her concerns and agrees to take part in an Alcohol-Free August with Brad. However, she drinks within a week of starting and makes a show at a concert rehearsal Brad has organised for his students. Although she apologises, Brad struggles to move past their issues.
Terese finally accepts that she has a problem with alcohol and Sonya Mitchell (Eve Morey) advises her to attend Alcoholics Anonymous, but she fails to do so. Brad and Terese argue and she tells him to leave. She later sees photos of him kissing Lauren and leaving her house in the morning. Terese confronts them both about their affair and accidentally pushes Lauren in the pool. Brad begs Terese to keep her appointment with a counsellor, before she tells him to leave. Terese blocks Lauren's plans to renovate Harold's. While the family are arguing, Brad and Terese's youngest daughter Piper (Mavournee Hazel) returns from Canada. The renovations at Harold's go ahead when it's discovered that Terese signed a document authorising them. Paul offers Terese a room in the Eclipse Apartments, which she declines, to spite Brad, as he has moved in with Lauren. Terese is upset when Lauren lets slip that she and Brad are now together, and becomes the prime suspect when Harold's is trashed on the day of its reopening. Terese attends the a sleep-out to save Erinsborough High, where she sees Brad and Lauren kissing in the corridor. When a fire breaks out, Terese and Lauren are trapped when an explosion causes some lockers to fall on them. Brad rescues Lauren, but he cannot free Terese and tells her he will come back for her. Terese is rescued by the fire fighters and has to undergo a skin graft due to serious burns on her shoulder. She tells Brad that she knows he chose Lauren over her, but she decides to keep quiet. However, their children find out and turn against Brad. Shortly after coming home from the hospital, Terese develops sepsis and Brad vows to help out more while Terese recovers.
Terese invites Paul to live with her after he loses ownership of Lassiter's, despite a conflict of interest as Terese's new boss, Julie Quill (Gail Easdale), is an old enemy of Paul. Lauren nominates Terese for a "Women in Business Award". Wrongly assuming Brad and Lauren are back together, Terese kisses Paul and tries to seduce him, only to change her mind at the last moment. When Paul keeps trying to undermine Julie, Terese, caught in the middle, chooses her job over her friendship with Paul, and asks him to move out. The hotel boiler explodes and Josh is killed in the ensuing destruction, devastating Terese. Paul supports her and tells her he loves her, but she is horrified when Paul is later accused of being responsible for the explosion. Believing he is guilty, she tells him she hates him. Terese bribes Cecilia Saint (Candice Alley) to tell the police that Paul confessed. She tells Brad and he decides not to report her. Terese attends an AA meeting, where she admits to being an alcoholic. She befriends and dates Walter Mitchell (Greg Stone). At Paul's trial, Terese drinks and later admits to having bribed Cecilia to commit perjury. She is charged with perverting the course of justice and sacked from her job by Julie. Walter also breaks up with Terese, leading her to drink heavily and collapse in the laundry room, where Piper finds her. Lauren and Karl help revive Terese and look after her. She admits that she thought she would feel better with Paul is prison, but nothing has changed. She then leaves for a health retreat in Tasmania. Terese refuses to let Piper attend the school formal with Tyler Brennan (Travis Burns), as he is too old for her. At her court hearing, Terese is given a suspended sentence. She begins a romance with Ryan Prescott, who is much younger than her, leading Piper to accuse her of hypocrisy. When Terese learns Ryan used to run a lingerie cleaning business, she breaks off the relationship and fires him from his job at Lassiter's. Paul tells Terese that he plans to buy back Lassiter's and fire her, so Madison Robinson (Sarah Ellen) suggests Terese launch a counter bid. Lucy accepts Terese's offer and Madison goes to New York with her to oversee the paperwork on Terese's behalf. Terese and Brad hold a party to celebrate their divorce, which is ruined when Piper plays footage of Paige and Tyler's one-night stand. Terese then sees Brad proposing to Lauren, but gives him her blessing. Terese hires renowned chef, Solomon Carter, for Lassiter's, only to learn that Paul has poached him. Terese has a date with Gary Canning and then discovers that Gary is spying for Paul. Terese decides to have musical acts at Lassiter's. Terese learns that Ryan has planted hidden cameras in the hotel rooms. The cameras are removed and the footage is destroyed. Later she learns that she's destroyed evidence which may support Xanthe's claim of assault against Cooper. She obtains a copy from Ryan and sends it on USB stick to Xanthe. Terese hosts an exhibition entitled "Treasures of Hollywood" at Lassiter's. A tiara is stolen. Terese suspects Gary and stands him down. The tiara is found in Leo's possession and he confesses. It's later discovered, however, that Jimmy stole it. Terese and Gary begin a relationship.
The character has received a mixed response from television critics. A TVTimes reporter reckoned that Elmaloglou's casting proved that there was still a shortage of actors in Australia. When Terese stated that she and Paul would make a good team, the reporter commented "You live and learn, love." Daniel Kilkelly from Digital Spy observed that Terese had received a lot of positive feedback and Elmaloglou was pleased that viewers were loving her character. A New Idea columnist thought Terese was "tough" and branded her a "feisty mum". A Sunday Mail reporter noticed "The fued [sic] between Terese and Paul shows no sign of abating as we move in to the New Year."
A writer for The Sun newspaper's TV Magazine noticed that Terese was left "frustrated and helpless" during Imogen's eating disorder storyline. In February 2014, another writer for the publication stated that everyone wanted Terese to get her job back, explaining "Without her at the helm, Lassiter's is falling apart." After Lauren revealed that she and Brad had a daughter, Laura Morgan from All About Soap said she was "pretty sure possessive Terese won't be happy about her hubby spending time with his former flame." Morgan then speculated as to whether Terese would turn to Matt for comfort, saying it would be "a brilliant twist to the tale!"
Morgan later questioned Terese's personality transplant, saying "The ballsy businesswoman has always been no-nonsense and forthright (and we love her for it), but since discovering Paige is Brad's daughter she's turned into a full-on soap bitch. Terese reckons Paige is 'dangerous' – but sorry, we can't agree with her." Morgan accused Terese of being jealous and did not think her actions were for Brad's benefit at all. In August 2015, Melinda Houston of The Sydney Morning Herald observed that Terese was "often a prickly character, hard to love (her recent affair with the bottle hasn't helped) and tonight Brad puts a few things to her that are hard to refute."
In May 2016, All About Soap's Mark James Lowe praised Elmaloglou and her character, stating: "In a street occupied by saintly Susan and vanilla Lauren, we thoroughly enjoy Rebekah Elmaloglou's depiction of multi-layered Terese. Mrs Willis's grief and pain over losing son Josh has been heartbreaking – and we know it's bad, but we love when Terese gets sozzled."