This article contains a lot of spoilers for the seventh season of Game of Thrones. A LOT. With that in mind, don't even think about reading on unless you're up to date with the HBO show. You've been warned…

The season finale of Game of Thrones aired on Sunday night, and it was as epic and thrilling as fans had hoped. We found out Jon Snow’s real name and ancestry; saw Arya (Maisie Williams) and Sansa (Sophie Turner) team up to serve a very cold dish of sisterly revenge; and were forced to question how we really feel about aunt-nephew incest.  

One of the biggest moments of the episode, however, stemmed from the peace summit in the Dragonpit. The various warring GOT factions met to discuss how they are going to tackle the White Walkers, and after a lot of tense debate, Cersei Lannister (Lena Headey) agreed to put aside her differences with Daenerys and Jon and send her armies to join the fight against the dead.

However, when Cersei later met with Jaime – her twin brother, long-time lover and the father of her unborn child – she revealed that she didn’t intend to fight alongside the Northerners at all. Instead, she planned on betraying Daenerys and Jon and staying at home.

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Jaime was more than a little horrified: perhaps naively, he had taken his conniving sister at her word. He told Cersei that he was going to ride North anyway. Outraged, she accused Jaime of treason. He challenged her to kill him; she said that OK, fine, she would.

However, rather than accepting his fate, Jaime finally did what everyone has wanted him to do for years: he stood up to Cersei.

“I don’t believe you,” he told his sister, before pushing past her and striding out of the room.

Nikolaj Coster-Waldau plays Jaime, and in a new interview he says that he thinks this scene marked a turning point in the Lannister siblings’ messy relationship. The Lannisters’ weird twincest love has been one of the most consistent relationships of GOT, and Jaime has been in thrall to Cersei since GOT began – but Coster-Waldau believes that he’s finally reached the end of his tether with his sister.

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“That was a great scene, really, because we’ve been waiting for that moment a long time,” he tells the Huffington Post. “There were so many other times when I thought that would be it, time for him to pack his bags, but I guess she finally took it one step too far.”

Coster-Waldau says that Jaime “understood the threat [of the dead], and he understood that clearly if they don’t all work together, they don’t stand a chance. And the fact that he knows his sister saw and recognized the same threat and her calculations led her to the exact opposite result – it’s just shocking.

“I don’t know why it took him so long to realize what the rest of the world always knew – that she is a crazy monster – but he finally did.”

The actor adds that when he said the line “I don’t believe you anymore”, he was trying to convey one thing: that not only has Jaime finally recognised Cersei’s true colours, he actually doesn’t love her anymore. Like, at all.

“My subjects as an actor was ‘This is it. I don’t believe in you anymore. I don’t believe in this, you and me. I don’t love you anymore’,” he says. “That’s how I played it.”

Coster-Waldau says that he doesn’t yet know if his interpretation of Jaime’s words will be backed up by storylines in season eight, but as far as he’s concerned, his character is over being manipulated by his sister.

“I’ve done that before and then you find out that’s not what they [the screenwriters] intended, but, you know, that was kind of my intention that that was it,” he says. “She’s obviously always going to be a huge part of him and there won’t be a day where he won’t be thinking of Cersei… [But] I think the whole ‘I’m in love with you’ thing is not really there – it’s gone.”

Given that Cersei has got used to being able to control Jaime for seven seasons – and that she is, as Coster-Waldau says, “a crazy monster” – we’re willing to bet that she won’t take her brother’s defection lying down. Roll on season eight…

Images: Helen Sloan/Macall B. Polay/HBO