When Game of Thrones returns this summer, there’ll be more than a few surprising alliances in Westeros — and we have exclusive info on all of the unexpected twists and turn (and big-ass dragons) that make the show’s seventh season the most fiery yet.

WINTER IS HERE. Jon Snow pushes against a howling whiteout blizzard as he trudges deeper into the desolate North, squinting against the wind, wrapped in heavy pelts, leading a collection of shivering comrades. His team is crossing a frozen lake, about to face an enemy unlike anything we have seen before—not on Game of Thrones, not anywhere. The sequence will likely prove fatal for at least one character and play like “a shark attack on dry land,” as director Alan Taylor puts it.

But there’s one thing particularly jaw-dropping about this scene, and it’snothow a desolate Belfast quarry was transformed by an Emmy winning production design team into a replica of an Icelandic wasteland that’s so convincing you feel certain you’re going to slip on its “icy” surface. And it’s not how the actors gamely inhale bogus paper “snow” for hours as it’s blasted into their faces by giant fans (actors cough and blink between takes, making jokes about getting “white lung”). Nor is it even Jon Snow himself, actor Kit Harington, whose famously wild hair is curiously uncovered despite his character trekking through a blizzard (“Jon gets to not wear a hat—which isn’t realistic, but you want him looking like a hero,” Taylor explains).

No. What would truly shock any fan visiting the set is the spoiler loaded collection of familiar characters who are now forming a circle with Jon—swords drawn, ready to fight and die together. It’s a group who, for the most part, do not like each other. And it’s only one example of the unprecedented pairing of fan favorites that will cause all sorts of buzz this season. “There are a whole bunch of reunions and first-time meetings that people have been waiting a very long time to see,” says showrunner Dan Weiss. “We just want to do justice to the work that these actors have done building these characters over so many years. You want to give them as much as you can.”

Who meets who during season 7—and why—are closely guarded secrets (though not as guarded as the production would like, and we’ll talk about those leaks later). Thrones last left us on multiple cliffhangers, with Daenerys Targaryen (Emilia Clarke) setting sail with Tyrion Lannister (Peter Dinklage) and the Greyjoys to wage war in Westeros; Cersei Lannister (Lena Headey) ascending to the Iron Throne after her explosive bloodbath coup; Jon Snow reclaiming the Stark home of Winterfell alongside Sansa Stark (Sophie Turner), her guardian Brienne (Gwendoline Christie), and her creeper-mentor Littlefinger (Aidan Gillen). There’s also newly powered-up Bran (Isaac Hempstead Wright)—a.k.a. the all-seeing Three-Eyed Raven—up at Castle Black, and Arya (Maisie Williams) touring around Westeros.

What happens next in this epic tale of ice and fire is not what you’d expect—and not what Weiss and fellow showrunner David Benioff expected, either. Despite years of meticulous long-term story planning, their concept for season 7 dramatically changed once they sat down to write their scripts early last year. The season was supposed to be a relatively low-key buildup to an action-filled eighth and final run. “We always thought this season would have less action and more conversations,” Benioff notes. “And then we started realizing all the conflicts that were about to occur.”

Instead, season 7 turned out to be the fastest-paced collection of episodes Game of Thrones has ever made. Even cast members were shocked when they read their scripts. “I feel like I’d been lulled into a different pace,” says Nikolaj Coster-Waldau, who plays Jaime Lannister. “Everything happened quicker than I’m used to. I’m like, ‘Already? Now?! What?!’ A lot of things that normally take a season now take one episode.”

Harington even admits to being “worried,” at least initially. “This is changing what Thrones is,” he says on the set in full costume aside from some amusing-looking Crocs to relieve his feet. “It’s so different than what everybody is used to. It’s quite exciting.”

It’s tempting to assume that the show’s faster pace is because producers made only seven episodes this year instead of the usual 10 (HBO, naturally, wanted more). But the Thrones writers say their warp-speed narrative was driven by the characters’ conflicting agendas. “Things are moving faster because in the world of these characters, the war that they’ve been waiting for is upon them,” Weiss explains. “This urgency is from within the story rather than any external decision.”

Put another way: Once Dany and her dragons disembark in Lannister controlled Westeros, the only logical outcome is all hell breaking loose—and it does. “Dany in Westeros makes Game of Thrones a new show,”coexecutive producer Bryan Cogman declares.“It has this amazing ripple effect throughout every story line that’s very exciting to explore. There’s a pace and urgency that’s very palpable. This is the endgame.”

Which led to another surprise for the show’s cast: Despite fewer episodes, the core cast is getting more screen time than before. “When I first read this season, I thought, ‘Damn, I gotta learn some lines!’” Clarke marvels. “We’re actually filming longer now. I don’t know how that’s happening.”

IT SEEMS CHARACTERS COMING together means Thrones no longer has to make room for so many separate story lines (“Everyone gets a bigger slice of the pie,” as Harington puts it). Plus, as Weiss points out, “when you kill a couple dozen characters, the people who are left just by default need to carry more dramatic weight.” And in an effort to make the season as epic as possible, producers spent just as much time and money to shoot sevenepisodes as they usually spend to make 10. Still,the season might not have been so difficult to pull off if Thrones weren’t a production obsessed with topping itself. Last season’s final two operatic hours directed by Miguel Sapochnik (who is not back this season but is likely to return for the final run) set an intimidatingly high bar. “It’s incredibly hard to top those two,” Benioff admits. “Trying to live up to that standard is certainly added pressure.”

Here’s howThrones is trying, exactly: There is a battle scene involving dragons (which are now the size of 747s, with firepower to match) that strives to give us a soldier-level view of what it’s like to face fully grown airborne monsters. There is the show’s most elaborate sea battle yet. The Night King and his army of the dead continue to cause trouble. And there’s that sequence in the frozen North with Jon Snow and his companions. But it’s the whomeets-who of it all that should generate the show’s most talked-about moments, even though writers were very careful not to overplay their hands.“More than once we had a conversation where we were like, ‘Could so-and-so possibly ever have a scene with so-and-so?’” Cogman says. “But as fun as that would be, sometimes it just wouldn’t make sense— they couldn’t be in a room together without killing each other.”(Which on Thrones often happens anyway.)

Some of the pairings have seemingly leaked online, with paparazzi relentlessly stalking the show with long-distance lenses and drones. Certain corners of the internet delight at each new reveal, while most fans strive to avoid spoilers. The cast and producers get annoyed by the attempts and struggle to understand why anybody would want to experience their months of obsessive hard work diluted to a blog post. It’s enough to offend even a professional gossip-trader like the Master of Whisperers himself. “It’s the a–hole element of your profession, and they get it all wrong anyway,” says Varys actor Conleth Hill. “They’ll take a photo of two actors between shots and they’ll say they’re in a scene together.”

The end result is a season that, as HBO programming president Casey Bloys puts it, shouldn’t have fans feeling like they’re getting any less Thrones than usual. “When people see it, they will be satisfied,” he predicts. “There will be less obsessing about how many episodes because it does pay off. The story is really huge, and it looks fantastic.” Previews have revealed that Daenerys takes up residence in Dragonstone, which was the Targaryen ancestral home before doomed Stannis Baratheon took over. “I get a new throne; I’ve upgraded from the bench in Meereen,” Clarke says. “But Dany forces you to think about her objectives this season.”

Tyrion remains by her side and will be challenged to rein in Dany’s fire-blooded impulses. Dinklage confesses he’s relieved to escape the isolation of Meereen. “I get to work with some actors I haven’t worked with in many years,” he teases. But there is the matter of his character’s family—Tyrion didn’t exactly leave on the best of terms after the whole patricide thing. “He’s returning to the land of a brother he loves and a sister he dot-dot-dot,” Dinklage says. “He’s bracing himself.”

And you can expect Dany and Tyrion’s presence to not go unnoticed by Cersei, who isn’t about to wait around for dragons to firebomb her bedroom. “Last season I was thinking, ‘Surely she’s going to die immediately [after Dany arrives],’” Headey says. “But she’s listened to her dad and has put alot of things in place politically. Her story manages to be more surprising than you can conceive of.”

How to handle this seemingly lopsided contest between Cersei and Dany was one of the challenges faced by the writing team, who have long left behind the narrative in George R.R. Martin’s novels. “She didn’t get to be the first queen in Westerosi history without being clever,” Benioff says. “She’s a survivor. She certainly knows the odds are stacked against her. And it’s her mission to find a way to even the odds.”

Cersei’s relationship with Jaime likewise seemed destined for destruction after last year’s finale where she blew up the Sept and their son committed suicide. But there’s remarkable strength there as well. “When Jaime came back, I thought he’d have been more like ‘Okay, honey, you’re on your own!’” Coster-Waldau says. “But he loves her and is loyal to a fault. The question is: How far will that go?” Oh, the things Jaime does for love.

Up at Winterfell, Sansa will continue her gothic-toxic relationship with corruptive seducer Littlefinger, who continues to try to drive awedge between her and Jon.“It’spretty obvious what my game is there,” Gillen says. “But at the same time, my character is becoming quite aware that Sansa is becoming as bright as me and wary of my manipulations of her. They use each other. They enjoy each other. They’re onto each other.” Adds Turner, “There’s this underlying tension all the way through, it’s like a f—ing horror movie.”

At least Sansa still has the protection of Brienne, who is forced to unsheathe Oathkeeper more than once this year (and for unpredictable reasons).“Brienne will continue to fulfill her oath in totally unexpected ways,” Gwendoline Christie says coyly. “Everyone’s going to go mad when they see this season. It’s not just about heaping people together—everybody is where they are for a reason.” And yes, there’s some more Brienne-and-Tormund awkwardness as well.

For a show that’s long given nearly every main character their own adventure, there are surprisingly few stragglers left—just Bran Stark, Arya Stark, and Samwell Tarly.

Crafting Bran’s adventure was the trickiest, given how last year the Three-Eyed Raven endowed the young Stark with visionary powers that not only showed him events from Westeros’ shrouded past, but showed he could change those events as well. To keep a lid on Pandora’s box,the writers tooka cue from Luke Skywalker’s arc in Star Wars: The Empire Strikes Back— “incomplete was your training,”as Yoda put it— and inexperience hinders Bran from being too powerful. Still, producers dubbed him “Dr. Branhattan” on the set, in a Watchmen nod. “Bran the Broken is now broken in more ways than one,” Benioff says. “He’s got serious challenges dealing with all the stuff happening in his mind.”

Arya’s story is so top secret we can’t even hint at what she’s doing after brutally crossing Walder Frey off her list in last year’s finale. Unlike Bran, the lone wolf’s training is pretty much done. No longer a cocky student, Arya is a stone-cold killer. “She’s found her calling in life and is very effective at what she does,” says Williams, who’s coming off her first Emmy nomination last year. “She’s more learning about the political game this year, which she hasn’t had to play any role in before.”

Sam (John Bradley) might be the season’s most isolated character, having traveled to Oldtown with Gilly (Hannah Murray ) to study at the Citadel. There he meets a potential new father figure, a powerful Maester (Jim Broadbent, as the show’s most significant new character this season). “Sam shows up to this amazing place where he thinks he’s going to get all the answers and his talents are going to be put to good use,” Cogman teases. “But this ain’t Harry Potter, and the Maester is not Dumbledore.”

This being Thrones—and the penultimate season, no less—you have to figure not all of these fan favorites are going to make it out alive, and even fewer will still bestanding in thefinal scene of season8. The cast isn’t blasé about this. After spending nearly a decade in Westeros, each actor genuinely hopes their character makes it to the end. “The first thing I did when I got the scripts this year is go to the last page of the last episode and then work my way back to my name to see if I survived,” Dinklage says (and of course he’s not telling).

What’s going to happen in the final season—which we’ve confirmed will be six episodes—is something only the writers know (and they don’t tell anybody). Many of the cast privately speculate about those last hours among themselves, brainstorming story possibilities that range from the eerily plausible to the rather silly. Given what happens in the season 7 finale, however…there is a single common assumption among the actors about what happens in the final season. Their prediction is just one word, actually: “Carnage.”