Sunita's relationship with Dev (Jimmi Harkishin) well and truly hits the rocks in the coming days, but after the mum-of-two drowns her sorrows with a huge drinking session, things go from bad to worse as she ends up being arrested for a public order offence.
When a disgusted Dev refuses to pick Sunita (Shobna Gulati) up from the police station, Karl secretly heads down there to help her out instead. However, he's in for a surprise as Sunita suddenly kisses him…
Digital Spy recently caught up with John Michie, who plays Karl, to hear about the story twist.
What's your take on Karl's attraction to Sunita?
"Well, Karl is a serial flirt - he likes a lot of women! But with Sunita, there's also a shyness about her that he's quite attracted to. Karl's not like that himself, but he finds it intriguing - and he also likes the way that Sunita dresses when she comes into the pub. She's quite sexy in a demure way.
"Sunita is very different from Karl's partner Stella, and he's going through a bit of a turbulent moment in his relationship. So Karl's way out of everything is to just look for another woman!"
Do you think it was only a matter of time before we saw Karl's womanising side?
"I think so! Karl has probably been with Stella for longer than any of his previous partners, but we reckon that's only about four or five years. So it possibly was just a matter of time, and the perfect moment has arisen because Karl's not in a stable place anyway at the moment. His gambling addiction means that he's not the Karl who first arrived at The Rovers, when everything was good in his life."
"Yes, there's a very kind side to Karl. You may not often see it, but he's actually quite caring. So when Karl sees that Dev isn't going to pick Sunita up from the police station, he's quite shocked and goes to get her. At this point, he is just genuinely helping out - he's not chasing her."
What happens next?
"Sunita is in a highly emotional state, so she comes onto Karl. It doesn't go very far before they pull away, but then Karl starts to regret the fact that it hasn't gone further! You'll see that Karl ends up feeling a bit confused, and that's really the beginning of the relationship that is coming up between him and Sunita.
"At the start, though, it's a case of Sunita and Karl getting their signals mixed up. Karl is thinking of Stella as well, so it's quite a strange and confusing situation."
Are you enjoying working with Shobna?
"Yes, she's really easy to work with and she's a lot of fun. We rehearse our lines on our own sometimes and work on the scenes together, to make sure we've got it all right. It's very quick on Corrie - you've got to turn up on the set knowing what you're doing. So we get on really well and we're really enjoying working together."
"The main problem between them is that Karl is hiding his gambling, so he's basically living a lie and that's causing stresses and strains to come out in his relationship. Stella doesn't know that Karl has a problem, so she can't understand why Karl is behaving the way he is.
"I've researched gambling addictions with help from Coronation Street and support from Gamblers Anonymous. I've learned that it's an incredibly afflicting addiction - it really does change your whole life around. Just because you're not taking a substance like alcohol or drugs, it doesn't mean to say that your whole personality isn't going to change rapidly. Karl is going downhill as a person, so that's the reason why he and Stella are not getting on."
Karl also steals from the till at The Rovers this week, doesn't he?
"Yes, his problem is spiralling out of control now. But Karl justifies it to himself, thinking that he's just borrowing the money. Karl is a big-time, big-hit gambler now, and he almost thinks that he has some sort of supernatural power to win.
"From Karl's point of view, if he takes money from the till, that's not stealing - he genuinely believes that he's going to put it back and win even more. He thinks Stella will be really pleased with that, as it'll help to pay the mortgage off on the pub. So in his twisted mind, he's helping her!
"It's an unbelievable addiction, and just because you might not see Karl going down to the casino or down to the bookies in every episode, it doesn't mean to say that he isn't doing it! He's actually going all the time, and you're only seeing the tip of the iceberg."
"In a way, I think you have to sympathise with any character that you play. I've found that in the past, even when I've played characters who are darker and more dangerous. There's always a side to them or something in them that you can sympathise with, in order to make the character believable.
"I can sympathise with the fact that Karl is an addict. It's as simple as that - he has an addiction. People who are addicts need help, and they also have to help themselves. But sure enough, they tend to only help themselves when they reach rock bottom! So I have a sympathy with the fact that Karl is diving deeper and deeper to the bottom - he almost has no control over it."
You've been on our screens since last summer. Do you feel like you've settled in well at Corrie?
"Yes, I'm really enjoying it. It's great fun here and it's like a big family. It's also nice now to have a bit of a meatier story to get my teeth into. It's a funny thing, but when I first came onto this show, I felt at home straight away - I really did."
How has Corrie compared to your previous work?
"I suppose what's different is that there's 65 actors in this - that's a huge amount of actors all potentially playing leading storylines at some point or another. It's great that there's always loads of people in the green room every day.
"Corrie's very vibrant, very lively, and very funny - everyone has a laugh. We don't take the business seriously, but we do take the work seriously. There's an irreverent and hardworking atmosphere here, and that suits my personality down to the ground."
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Coronation Street airs Mondays, Thursdays and Fridays on ITV1.