With the pair both feeling down about their lives, Rachel and Jai (Chris Bisson) seek comfort in each other after hours at the factory - drinking together before their unlikely bonding session turns to passion.
Rachel and Jai are plagued with regret the next morning, but with hints that the encounter will lead to a huge story for the duo, it seems that this is just the beginning of a longer journey.
Gemma Oaten, who plays Rachel, recently chatted to Digital Spy about the drama in store and her time at Emmerdale so far.
What was your initial reaction to Rachel and Jai's new storyline?
"I was told about this storyline before Christmas, and I was completely shocked. A lot of people have said to me, 'I never saw that one coming!' Neither did I, because before Rachel got the cleaning job, her path had never really crossed with Jai, Charity or any of the Sharmas.
"So it has definitely floored me a little bit, but in a really exciting way. Also, I know where the story goes and how it all pans out, and it does turn into something pretty big."
Does Rachel have any feelings for Jai, or is it just a drunken mistake?
"I think people will see that it really does come from nowhere. Rachel has never had an agenda with Jai at all - she's just had a really rubbish day. She's been kicked out of her flat, and she's just found out about David and Alicia too, so she's a bit down in the dumps.
"Rachel is working at the factory and when she comes in to clean the office, she sees that Jai is on his fifth whisky! He asks her to join him and she's not really sure at first, but they do have a drink and then it all goes from there. The two of them sleeping together honestly comes with no build-up at all."
How does Rachel feel the next morning?
"Rachel bitterly regrets what she's done. She's such a moralistic girl, so she feels awful that she's slept with a married man - whether Charity treats her like rubbish or not. So there's no romance there at all, it's just a huge mistake that they both regret."
Jai is quite cruel to Rachel afterwards, isn't he?
"Yeah, Jai says all the wrong things, implying that he wouldn't have touched Rachel with a bargepole if he hadn't been drunk! He's obviously mortified that he's done this to Charity, but he does keep slipping up and putting Rachel down.
"That's really difficult for her, because she's never had anybody reciprocate her feelings - as we've seen with Marlon and David. So Jai really does rub salt in the wounds for her and she comes out of the situation feeling very vulnerable, angry and upset."
Rachel threatens to tell Charity the truth at one point. Is she serious, or just trying to scare Jai?
"That happens the day after, when Charity is being horrible to her. When she's cleaning, Charity just treats Rachel as a dogsbody, and a row starts to escalate. That's the impulse for Rachel to say, 'Do you know what? I might just tell her'.
"But deep down, Rachel knows that she would never do that. It's just a threat that comes out of being angry. She actually says later on, 'I would never tell Charity, because I'm not that kind of person - but she's going to have to back off because she's treating me like rubbish!'"
Jai also tries to buy Rachel's silence! How does Rachel react to that?
"Oh, she's not happy! (Laughs) He's already insulted her, so the worst thing he could do next is offer her money. She is just incredulous over what he's suggesting. It shows that he doesn't know Rachel very well - that is not the kind of girl she is. She feels absolutely trampled all over, yet again, when he does that to her."
Are you excited about the bigger stuff this story is leading into?
"I'm really, really excited! I've been in Emmerdale for a year now, I've done bits here and there, and I think it's great that they've brought me in so slowly. But now I've got something to really sink my teeth into. I can't say much about it, but I can't wait for it all to unfold.
"We're filming it at the moment, and the last two weeks have just been insane. I've been in work from 7am until 7pm six days a week, but it's so flattering that they think I can handle it. I feel very lucky and blessed."
The viewers have usually been on Rachel's side in her stories so far. Do you think they'll still have sympathy for her now that she's made a big mistake?
"I've thought a lot about this and it's started already now that the spoilers have been coming out for the storyline. There are a lot of people who are jumping to conclusions, but I think you have to really watch and see how it plays out.
"I think there will be sympathy for Rachel, because it's just come from a feeling of loneliness. I'm sure there will be people out there who think, 'No matter what, she's done wrong', but that's something Rachel and myself are going to have to deal with.
"She's not perfect and she makes mistakes like everyone does, but hopefully people will see that she's not malicious with this and she has no agenda. She's not out for money, she's not out for blackmail - she's just made a mistake that she bitterly regrets."
Your other big story has been Rachel's involvement in the recent Sandy and Ashley plot. Do you think Rachel will ever forgive Ashley?
"When our producer Stuart told me about the Sandy storyline, I didn't realise how important and big it would be. It wasn't until I started to read the scripts that I felt a huge sense of pride that they'd actually entrusted my character - and myself - with something like that.
"I think what they've done with Ashley is brilliant. I remember being in the thick of it when John [Middleton] was playing all of the really difficult scenes. It was difficult for all of us involved and we thought, 'How can he ever come back from this?' But the scriptwriting is so brilliant, as it shows so many different sides.
"I also think that Rachel has a good brain and a good heart, so she sees all sides to things - and I think she could forgive Ashley, to be honest. I've played scenes already where Ashley has been around and Rachel doesn't give him grief. She just thinks, 'Right, I did the right thing, I spoke up, what's done is done, Sandy is alright, let's move on'. I think that's the sort of girl she is."
Does Rachel still have feelings for Marlon?
"I think they've come to an understanding and a middle ground now. I think she's let that one go and she knows to resign herself to the fact that Marlon never held that torch for her - he held it for Laurel. I think it's the same with David - she knows the score with him, too.
"Luckily, Rachel has managed to keep her friendships. I think she doesn't expect too much because she's never had that much. I want her to have a love interest at some point!"
How do you feel about Emmerdale's 40th anniversary being on the way?
"I've watched Emmerdale all my life and I know it inside out, so to be here when the anniversary storylines are starting is so exciting. None of us know the storyline for the live episode yet, and none of us know if we're in it or not.
"It already feels like we're building up to something, though. We just got some new scripts yesterday and you can see in the writing that there's a momentum and pace. All of the stories are crossing and mixing together. It's a brilliant time to be here at the minute."
Who are your best friends on set?
"I'm very close to James Hooton, but unfortunately we haven't filmed together a lot recently. Obviously when I came in, the story was me having a go at his character Sam. Lucy Pargeter is like a big sister looking out for me, and then I've got people like Tom Lister, Nick Miles and Sian Reese-Williams, who I know I can go to for anything.
"I've sort of flitted between different cast members, but at the moment I'm having an absolute scream with Rachel's family - Alicya Eyo, Kelli Hollis and now we've got Liam Fox, who plays Dan. We've been filming so much together lately - which is nice, because I think there's been a separation on screen with Rachel and her family for quite a while, but they all start coming together again."
Do you enjoy 'dressing down' to play Rachel?
"I'm really enjoying playing someone who is so far removed from my real-life persona. I feel very fortunate, because I can still live quite a relatively normal life - people don't recognise me. It can be difficult and it affects my confidence on set sometimes when I see a mirror and think, 'Oh God, I look awful!' But I do love it.
"It's quite an easy ride for me really - I spend five minutes in make-up and I'm done! I'd love to maybe see a makeover for Rachel further down the line, but I know Stuart loves Rachel's current look and he wants to keep it for as long as he can, so who knows if it will ever happen?"
> 'Emmerdale' spoiler: Jai cheats on Charity with Rachel
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Emmerdale airs weeknights on ITV1.