Leanne makes the surprising move after Nick (Ben Price) bites the bullet and declares his love for her, but the romance twist quickly leads to tension on the cobbles.
Still heartbroken following her split from Nick, feisty Eva (Catherine Tyldesley) feels betrayed by her half-sister. Peter (Chris Gascoyne), meanwhile, is livid that the Bistro boss will be so heavily involved in the life of his son Simon.
Jane Danson, who plays Leanne, recently chatted to Digital Spy about the storyline and what else is ahead for her character.
Why does Leanne decide to reunite with Nick?
"Well, after everything that's happened with Simon and Peter, Leanne is just craving stability and a normal family life - and I think she sees this as an opportunity to get that. Nick has got his business, he's got a secure place to live, and he loves her.
"On paper, it's all perfect. But the question is whether Leanne is just settling for him, or whether she actually loves him in return. That's going to be the main issue as they move forward."
Were you surprised when you first heard about the reunion, or did you always have a feeling the story would go this way?
"I think the possibility is always there when characters have had history. We've not really seen Leanne and Nick together since the affair, as she got her head down and tried to make a go of things with Peter. But as soon as everything fell apart with Peter, I suppose it was inevitable that Nick would be hovering in the background.
"When Leanne chose Peter, I don't think Nick's feelings went away. When Nick confesses his undying love for Leanne in the episodes coming up, she's the one in control. She's got to decide whether this is best for Simon and whether Nick can provide the continuity and family life that she's craving. In the end, she decides that he can and it would be a good idea!"
Does Leanne feel guilty about the Eva factor?
"I think, true to Leanne's history, she doesn't really feel guilty at all! (Laughs) I love the relationship with Eva. I think in some ways, Leanne sees a bit of herself in Eva. Eva is a bit more high-maintenance, but she's certainly got some of the same qualities - she knows what she wants and if she doesn't get it, she's very unhappy. That's what Leanne was like in days gone by.
"Of course, Leanne and Nick's reunion isn't going to go down well with Eva. The dust is only just settling on Eva and Nick's break-up, and Eva didn't really take it very well in the first place! When she finds out about the reunion, Eva puts two and two together and assumes that Leanne and Nick have been having an affair for some time. It all gets a bit messy."
What does Stella make of it all?
"I think Stella is caught in the middle of the situation. They're both her daughters, but obviously she knows Eva a lot better. She hasn't been there for Leanne and there's a lot that she doesn't know about her. There is a point where Stella says, 'Did you do this on purpose?' Obviously Leanne didn't, because she was genuinely focusing on Simon and wasn't planning this at all.
"Stella's in a bit of a difficult situation, because she doesn't want to rock the boat with Leanne too much, but I think she's probably siding with Eva a little bit more. So Leanne ends up feeling a little bit rejected by everyone. But she just thinks, 'You know what, I am going to be happy and I don't care what anybody else thinks'."
Peter gets quite jealous over Nick and Leanne's reunion. Is that just because of Simon, or is there more to it?
"It's mostly to do with Simon, but I think there's also an element of, 'I don't want you, but nobody else can have you!' The most heartbreaking thing for Peter is that he's seeing his son live with his arch-enemy. It's like a red rag to a bull for Peter. He's quite volatile at the best of times, but this is a step too far for him and he's not happy at all.
"Once again, there's a massive reaction from Peter in a really public situation. Last time, it was at the wedding when he told everybody about Leanne and Nick's affair. This time, he goes mad at Simon's birthday party and it's all a bit dramatic!
"But Peter is provoked a little bit, so I think what's really interesting about this story is that you can see it from everybody's point of view. You can totally understand why they all react the way they do, because they just wind each other up so much."
Nick suggests that Leanne should start working at the Bistro, so is there a new job on the cards for her?
"Well, she does work there for a while, but then she says that it's probably better if they don't live in each other's pockets. So Leanne ends up managing the bookies and sorting a few things out there. When Peter departs Weatherfield, Leanne takes that on because she's got an interest in the business. It's half hers, so she's not doing it for any reason other than the money involved!"
Chris Gascoyne has said that there's unfinished business between Leanne and Peter. Are you hoping they'll reunite in the long-term?
"Yeah, definitely. I think we liked them as a couple before they had all their rows and problems. Before the two affairs, all of their problems were very much within the home - revolving around Peter's drinking and the difficulties of being a parent.
"Once Leanne and Peter started cheating on each other, they lost a lot of trust. But I like to think of them as a bit like Ken and Deirdre - they can't live with each other, but they can't live without each other either. Further down the line, I hope they're destined to be together, but you just never know how it's going to go."
Leanne, Carla and Peter's story stirs up a lot of discussion, especially online! Do you like being part of a story that divides people?
"It's always nice when a story provokes a reaction. I also think this is a domestic situation that a lot of people find themselves in - the fight for a child, or being cheated on. It's not murders or big sensational events, it's more about everyday issues that people experience in real life.
"I think we've been given some great material over the last couple of years. The fact that people have talked about it is always rewarding. You always want to tell a good story, and if that captures people's imaginations, hopefully you're doing a good job!"
With Chris Gascoyne and Alison King both on four-month breaks from Corrie, is it strange not having them around at work?
"Yeah, it is a little bit! It's a bit like having a new job, or it being the first day back at school in a different class, as you get so used to working with certain people. Having said that, I think it will be great and beneficial for our characters to be apart for a while. By the time they come back to the cobbles, hopefully the story will have taken a different direction and it gives us further to go.
"In terms of me still being here, it means that I get to do scenes with people who I might not have worked with before. I'm working with Helen Worth a lot more at the moment, and I've not worked with her probably for about ten years, so that's always nice."
You've been at Corrie on and off since 1997, but the past couple of years have probably been your busiest - and you also won a big Soap Award in 2011! Has it felt like a noticeable change for you at work?
"It has, certainly since the tram crash and everything after that. I think Leanne has grown older and she's at a different stage of her life. Even though I've been lucky enough to be involved in some great storylines in the past, this current one has been the longest-running and the most enjoyable.
"It's lovely to get awards and it's nice to get recognition, because it's something that has never really happened before. But the most important thing is the material and delivering it well. Certainly the last couple of years have been the most challenging for me."
A lot of your Corrie co-stars are on Twitter. Would you ever be tempted to join them?
"It's a bit beyond me, really! I like the idea of it and I think it's lovely that there's so much reaction on there. At the same time, I don't think I'd deal with it if people were a bit nasty! (Laughs) I think sometimes it's best not knowing. If I was reading things about what people liked and disliked about what I was doing, I think I'd become conscious of it. So I'm fascinated by it, but I choose to leave it to the people who know what they're doing!"
Georgia Taylor, who played Toyah Battersby, left Casualty last year. Do you hold out hope that she could return to Corrie one day?
"Always! We're such great friends and always have been. As an actor, I'm sure she's keen to explore other things. But if the opportunity came up and it was the right time, I'd be really hopeful that she would say yes. Hopefully one day - I'd just like Leanne to have somebody around who would be really on her side 100% of the time! From my point of view, it would be fantastic."
According to the papers, the Corrie cast voted you as the best actor in the 50th anniversary live episode. Would you like Corrie to go live again?
"No is the short answer to that! (Laughs) Now that the dust has settled, I've actually recently watched the live episode for the first time in a long time. Being part of it truly was an amazing experience, but because of the special effects and everything that went into it, I'm not sure we'd ever create something as good again.
"The live episode was incredible and everything went really well, and it was great to have a big story in it. But I feel like it's done now and I don't really have any yearning to do it again - the pressure was immense!"
Is there anything that you'd be really keen to explore next with Leanne?
"Wherever Leanne goes, drama follows her - she's always been one of those characters. I would like to see her a little bit happier for a while, and I'd like to inject some of the fun back into her.
"Eventually, I think it'd be nice to see if Leanne could get the baby she longs for. It's been a bit of a struggle for her, and I think it'd put a few demons to bed if she had a little baby. But knowing Leanne, that'd probably go wrong as well!"
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