In the build-up to the big event, viewers have seen lies, deceit and blackmail revolving around Mercedes's affair with Riley's dad Carl, and with a number of characters threatening to expose the shocking secret at the ceremony, there could be fireworks ahead.
Here, actor Rob Norbury - who plays Riley - chats to Digital Spy about the wedding drama in store.
What was it like to film the big wedding episode?
"It was really good. It sounds odd, but sometimes we don't get many scenes where it's all of the Costellos together - there's often scenes where we're split up, or there's just two or three of us together. So for the wedding, it was nice for us to all come together and enjoy the big day!"
In the build-up to the wedding, we've seen lots of lies and secrecy involving many of Riley's loved ones. Does he have any suspicions that something isn't quite right?
"To be honest, I think Riley is wrapped up in his own issues at the moment. He's focusing on whether Jason will go to the wedding, he's had a showdown with Mitzeee, as well as all of the organisation and plans involved. Riley's excited, he's trying to enjoy it and be an adult about it. He's a bit too busy to spot anything suspicious!"
"I think while he's been caught up in all of this, his feelings have been very strong. He loves her to bits and he thinks that she's everything. But at the same time, with Riley being so young, there may be a degree of it just being puppy love.
"If the truth did come out about Mercedes and Carl, when all's said and done, the hurt would probably stem more from the deceit and the fact that his dad was involved, rather than Mercedes being the love of his life."
Hollyoaks fans have been looking forward to the wedding for some time. Do you think it'll be worth the wait?
"In my eyes, it was definitely worth the wait. Being part of a soap wedding is a big thing, and everyone at work has been really excited and positive about these episodes. Hopefully they should be good!"
We've always seen Riley as a nice guy. Could that change if the truth comes out at the wedding?
"Yeah, I think if anyone ever found out a secret like this, it would be very difficult for them to stay calm, nice and quiet! On the whole, Riley has been quite a nice, calm and laid-back guy - he's very relaxed and just happy to go with the flow most of the time. But if he does find out the truth, I think it could be one of the first times that we see Riley really lose it."
"Well, the fact that so many people know is really embarrassing. That would have to be a real sore point for anybody in a situation like this! It's hard to deal with this kind of thing at the best of times, but with everybody knowing about it, that makes it a lot more embarrassing."
You've said in the past that you really enjoy working with Jen Metcalfe, so whatever happens, are you hoping you'll continue to share scenes together?
"Working with Jen has definitely been great because she's just spot on. It's great to work with somebody who cares about the job and wants to do their best. After so many years here, she definitely knows what she's doing and she's amazing.
"It'd be nice to keep working with Jen, but at the same time, it's always great to keep things fresh and work with new people. That can often bring out new sides in a character. Sometimes if you work too much with one person, it can become a bit stagnant, but if things get mixed up it can make it more exciting for the viewers."
There's a great advert airing on Channel 4 and E4 at the moment for the wedding. What was that like to film?
"It was really good! If you look at the spoiler pictures, you'll see that the real wedding is quite a light and bright affair, so then to film that advert in pitch black with everything so dark and moody was a bit mental but really fun. We all had to try hard to keep happy, because it all felt a bit miserable!"
In Hollyoaks Later, we saw that there's a spark between Riley and Mitzeee. What do you think their feelings are for each other?
"I don't think either of them know, to be honest! We'll have to wait and see. Maybe there is something there between them, but I don't think either of them are ready to admit it at the moment and I don't know what circumstances would arise where they would ever admit it! Who knows?"
Warren Fox has caused a lot of trouble for Riley, but in real life, will you be sad to see Jamie Lomas leave the show?
"Oh yeah, I'll be gutted to see Jay go. We've done quite a lot of scenes together, especially recently with the late-night episodes. We've got quite similar interests, too. Jamie has obviously made Warren into a big character - they brought him back from the dead, so he must have been doing something right!
"With Victoria Atkin leaving too, that's two people who I've worked with quite closely who are leaving. But they both want to go on and do different things, which I can completely understand."
Are you excited about what's in store for the Silas storyline over the next few weeks?
"Definitely. Watching Jeff Rawle is great at any time, so it'll be interesting to see what's in store. Hopefully I'll have a little part in it at some point. Whenever that storyline comes to a head, I'm sure it'll be amazing."
"Definitely. For me, Miles was the stand-out in the late-night episodes this year. He was unbelievable. I told him at the time, when we were filming it, that he was killing it and then I sent him a little text to tell him again when I saw it on screen. Especially because he's a young lad, I thought it was important to make sure he knew how good it was.
"The storyline Miles did was a really tough one to film because when you're 18 years old, you haven't been through the traumas that were happening there. I thought Miles did an absolutely fantastic job."
Is it nice to have some more new faces on set at the moment?
"It is, and they've all settled in really well. We've all been out for a few drinks and a few meals together. I've been watching the new characters' scenes on telly and it all looks really good. I think the public will love them and it's always nice when new people come in because it keeps the show fresh and exciting."
Hollyoaks' wedding episode airs tonight at 7pm on E4 and Monday at 6.30pm on Channel 4.
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