Max's secret will be unveiled on Christmas Day when a scheming Derek (Jamie Foreman) ensures that his past returns to haunt him, just as he is planning to tie the knot with Tanya (Jo Joyner) again.
Show bosses are keeping full details under wraps until the episode airs on December 25, but the repercussions look likely to affect the Brannings way beyond Christmas…
Digital Spy and other journalists recently caught up with Jake Wood, who plays Max, for a chat about the upcoming scenes. Read on to find out what he had to say!
So Max isn't Kat's lover! When the mystery was running, did you hear from many fans who thought he was?
"Yes, an awful lot! I suppose that's no surprise given Max's history. Logically, it could have been any one of the Branning brothers with the way the story panned out - each of them had a reason to be with Kat.
"Having said that, I think it's great that this time it isn't Max. We've seen Max have affairs and be a bad boy, but given his behaviour over the last year and his commitment to Tanya through her cancer treatment, I think it's great that it's not Max on this occasion."
What can EastEnders fans expect from this year's Christmas episodes?
"I think everyone's in for a real treat - they're just fantastic episodes. Simon Ashdown is a master storyteller, and for me just reading the episodes was really exciting. I think the storylines have been beautifully mapped out over the past year, because there are going to be so many strands coming together at the same time. It's been really well planned."
Have you heard many fan theories over what Max's secret might be?
"Yes, there's lots of different things - there's been some wild guesses! That's great, though. The story has been going on since Max got back from Manchester, and it's remained a secret between him and Derek for all that time.
"I think when EastEnders does slow-burn storylines that play out for a long period of time, it really captures the public's imagination. That's certainly the case at the moment - it feels very exciting to be in the show and in the middle of it."
When were you told Max's secret?
"It's something that I've known for most of this year. There were only two or three other actors who knew - I think Jamie Foreman and Jo Joyner both did.
"When we started filming the episodes and could start telling other cast members, people were in shock. If that's the reaction from people who work on the show, hopefully it will have the same impact on the people who are watching at home."
Could this jeopardise Max and Tanya's relationship?
"Possibly! As we've seen, they've had their ups and downs. This could possibly put them under pressure, but we'll have to wait and see."
How do these episodes compare to the big Branning Christmas that we saw in 2007?
"I would say that these episodes are at least on a par with 2007, in terms of what I've read and the work that I've seen people do. Hopefully they can even surpass those, but who can say? We'll wait and see, but it's going to be huge."
How do you feel about Jamie Foreman's departure from the show?
"Jamie was such a pleasant guy to be around - he's a great actor and he played a great character. But the story arc had been mapped out for a year, and we always knew what it would be. We all knew what the conclusion would be, so it was no surprise when Jamie left, because that was always going to be the case when he joined.
"Although it wasn't a surprise, Jamie will be missed - both by the viewers and all the cast. But the events of Christmas will have huge repercussions, and in that sense, his presence will still be felt on that Square. The consequences of what happens will play out for a long, long time."
How does Max feel about Joey and Lauren's relationship?
"Max is surprisingly laid-back about that, I think. I was never sure how he'd react, as obviously Tanya knew for a long time before Max did. But all we've seen from Max so far is that he's incredibly supportive of Lauren. If Lauren is happy and settled, for him at the moment that's more important than anything else.
"Max is also aware of Derek's negative involvement, so if anything he wants to counteract that by being supportive. I don't think he's 100% happy about it, but if Lauren's happy and it goes against what Derek wants, then it's no bad thing."
How are you spending Christmas yourself?
"I've got a young family, so we'll just be really quiet at home. We're going out for lunch and then seeing family on Boxing Day. It'll be very relaxed and certainly not up to Max Branning's standards - I don't think I could cope with that!"
Are you looking forward to Ava and her son Dexter becoming permanent fixtures in the New Year?
"Yeah, we'll have to wait and see how it plays out, but they're very strong actors and great characters. I think they add a new dynamic to the Brannings and it's very exciting."
Do you think Jo Joyner's upcoming break means the end of Max and Tanya?
"No, not at all. But Jo's having a year out to look after the babies - she wants to spend a bit of time with her twins, and that's absolutely understandable.
"I think Max and Tanya work great together, but as we've seen, they also work well apart. For example, the Max and Vanessa stuff was great when Jo was on maternity leave. I think it gives them so many more options in some ways, as it puts the characters in different directions. I think it'll be absolutely fine."
Will Max be sticking around?
"I'm committed to the show long-term. It's been seven years and I'm still really enjoying my time on EastEnders. I don't see that changing in the foreseeable future. If they're still happy to have me, I'm happy to be there."
> Read the latest 'EastEnders' spoilers and news
EastEnders airs an hour-long episode on Christmas Day from 8.45pm on BBC One.