Dennis's sudden appearance comes as a surprise to his relatives, but it quickly becomes clear that he's keen to stick around in the area after being kicked out by his mum.
Confident and eccentric, Dennis soon takes a shine to bunny boiler Leanne Holiday - which makes things awkward when he moves in with her and Texas!
Dennis is played by Joe Tracini, best known for his previous roles as Darren 'DK' Karrimore in Coming of Age and Spike Bannon in My Spy Family. Here, Joe chats to Digital Spy about joining Hollyoaks and the part of Dennis.
You've been filming at Hollyoaks for a couple of months now. How's it all going?
"I love it up here. I didn't really know what to expect, as I've never really come into an existing cast before. With everything that I've done over the past seven years, I've joined at the start of the show and then seen it through to the end. So especially as Hollyoaks is so successful, I didn't know how they'd take to a new person and whether I'd be sitting in the corner on my own, not speaking to anyone!
"But they've been very lovely. I'm quite far away from home up here, but everyone's been really kind to me, they've taken me in and they've shown me how it works up here. I absolutely love working here - I really, really do."
How did the role come about?
"Hollyoaks phoned earlier in the year around March, asking me to come in to meet them and have a chat. We looked through the parts they had coming up and there wasn't anything there for me, but then they wrote Dennis for me. Apparently it's the first time they've ever done that, which is nice of them! It's really lovely.
"What's great is that they've put me in with the Savage family - with Dodger and Will. I think I fit in quite well with them. Not visually - I don't look like I come from the same gene pool as Danny Mac! But I get on with them really well."
Had you ever watched the show before joining?
"I had on and off. I've had various friends come into the show in the past few years. One of my best friends, Amy Yamazaki, was in it for two years - I started watching it a lot more when she came into the show. I know the show has really picked up and gone into another league recently - the viewing figures have been going up and up, and for good reason. The cast is so strong at the moment."
What kind of a character is Dennis?
"Well, he's certainly got an overinflated opinion of himself! He thinks that he's definitely as good looking as Dodger for a start, which is not true at all! He also loves crosswords and he works in a phone shop. He's relatively intelligent, but even though he's 23, he's lived with his mum for his whole life and he's never really grown up. I don't think he's had many friends to be honest, and I can see why!
"Dennis has a real tendency to make situations very awkward as well. He does have good intentions, but things often seem to go wrong when he's around."
Is Dennis just planning to pay a quick visit initially, or does he know from the start that he's there to stay?
"When he turns up, nobody knows that he's coming and he doesn't seem to have any intentions of leaving anytime soon. Basically, his mum's chucked him out because she's a bit sick of having him around the house, so he decides to go up and see the family. I don't think he's got a particular plan for how long he's going to stay, but he definitely knows he's not just staying for a couple of days.
"Dodger, in particular, is not very happy about that - so he shifts him off and makes sure that Dennis moves in with some other people as quickly as possible, especially as there's hardly any room in the caravan. Dodger shifts him out of the way as soon as he possibly can."
What does Will think about Dennis?
"Well, I think everybody's got that goofy little cousin who you can put up with at Christmas, but that's about it! It's fine when you're 6, but now that you're adults, you don't really want to talk to them! Dennis and Will haven't really got anything in common. Dennis can be quite taxing, too - he's grating after a short period of time. Well, that's the nice way of putting it!"
Does Liberty like him?
"Liberty loves him. Liberty tends to just go through life and accept things, so she's a big fan of Dennis's, which is nice. But Dennis is very unaware that he grates on anyone. He thinks that he's just being himself and having a nice time, when actually he's doing everyone's head in!"
Will Dennis be bringing a lot of light relief to the show?
"Oh yeah, completely. They've definitely not brought me in to start murdering people or anything like that! So I've been trying to be as vaguely humorous as possible. But what's quite nice - especially as they wrote the character with me in mind - is that it feels quite real and it's not slapstick. There's actually quite a lot of heart to him, and I've been getting as much serious stuff as I have humorous stuff. There's been a really nice balance."
Dennis is confident but does he actually have any success with the ladies in the village?
"I don't think he's the best at picking them! He's one of those people who will stay single until someone shows that they're interested and then he'll go for it. He ends up aiming his interest towards Leanne, but it doesn't go particularly well. But he doesn't give up! Dennis moves in with Leanne and Texas and it becomes very uncomfortable for all of them because he's so fixated on Leanne."
Has it been easy to settle into a new city for the role?
"I've lived in London for the past seven or eight years, but one of the things that I was most excited about was coming up here, as I've never spent any time in Liverpool before. I love it up here."
This is the first time that you've done a soap. Has it felt quite different from your previous work?
"Definitely. I've only really done sitcoms for the past six years. With sitcoms, even if you're doing a six-episode single camera shoot, you'll always get at least a week's rehearsal time. So the main change has been to not have that at all.
"It's a whole new way of working, but that's really exciting as an actor - especially when they're trying to give me funny stuff. It's a tight timeframe to make it funny which can be difficult, but it's fun and it's exciting. To be honest, I'm just lucky that they pay me for this. I'm waiting for the day where they wake up and realise I'd do this for free!"
Who are your best friends on set?
"I really get on well with everyone. Me, Danny and James [Atherton] hang about a lot. All of the new Freshers who have come in are all brilliant as well - I really get on with them. What's great is that even though there are so many different ages here, everybody gets on well with everybody else. We're like a little team up here, which is not what I was expecting to happen at all. I'm really pleased about it and I'm looking forward to staying for a while longer!"
> Read more Hollyoaks spoilers and news
Joe Tracini's first Hollyoaks episode airs on Tuesday, November 15 at 6.30pm on Channel 4.